subfactorial & derangement, an explicit approach

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  • เผยแพร่เมื่อ 20 ธ.ค. 2024

ความคิดเห็น • 123

  • @ThAlEdison
    @ThAlEdison 6 ปีที่แล้ว +19

    th-cam.com/video/skiS1VqOaCk/w-d-xo.html Venn higher than 3

  • @jay_sensz
    @jay_sensz 6 ปีที่แล้ว +4

    The Taylor series for e^-1 converges very quickly. That means that n doesn't have to be very large at all for it to be a good approximation. It seems that the following expression holds for all n>0:
    !n = floor(n!/e + 0.5)

  • @davidrheault7896
    @davidrheault7896 6 ปีที่แล้ว +2

    I just received my copy of the T-shirt, 3 weeks for delivery in canada.
    A note for the video, !n is EXACTLY n!/e when you use the round function, I mean instead of doing 'sup factoreo of 4 by recursive formula, we can do
    !4 = round (4!/e) = 9,
    |3 = round(3!/e) = 2
    !2 = round(2!/e) = 1
    !1 = round(1!/e) = round(0.37) = 0
    we can compute the digits of e by going high enough with the recursive formula, I did it high enough to compute 1000 digits of e :) Basically, you just need to divide the factoreo by the derangements

    • @blackpenredpen
      @blackpenredpen  5 ปีที่แล้ว +1

      Oh yea. I am actually aware of that. Thanks for letting me know and hope you like the t shirt.

  • @Goku17yen
    @Goku17yen 6 ปีที่แล้ว +17

    holy crap, that intro looks surreal

  • @i_am_anxious02
    @i_am_anxious02 6 ปีที่แล้ว +7

    Oh my gosh, you are making such unique intros and thumbnails, u r being so creative

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว

      Thanks to my subscribers for the intros. I do the thumbnails myself : )

    • @i_am_anxious02
      @i_am_anxious02 6 ปีที่แล้ว

      blackpenredpen your an awesome guy with an awesome community :)

  • @GourangaPL
    @GourangaPL 6 ปีที่แล้ว +21

    you said "but unfortunately i need more space", combining it with the sentence you always say, it would be "i don't like to be on the bottom, i like to be on the top, but unfortunately i need more space"... hmmmmm.......

  • @quantumcity6679
    @quantumcity6679 6 ปีที่แล้ว +10

    The new intro🔎 looks awesome!! 😘👌🤘

  • @goliathcleric
    @goliathcleric 6 ปีที่แล้ว +9

    The new intro looks great!

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว

      Meliodas The Sin of Wrath thanks!!!! A subscriber did it for me.

  • @nicolassamanez6590
    @nicolassamanez6590 4 ปีที่แล้ว +2

    yo, i actually know how to do this
    if you look at a three-way venn diagram, you can draw it by starting your way inside-out; draw a reuleaux triangle, then complete the 2-way intersections, then finally the circles.
    you can generalize this for any n-gon. start out with a reuleaux (for odd n) or reuleaux-esque (in case of even n-just make the sides circle arcs) polygon, and work your way up from there, drawing in the intersections in increasing order, finishing with the circles.
    so many years of doodling in math class finally paid off, it seems

  • @NuptialFailures
    @NuptialFailures 6 ปีที่แล้ว +6

    I really love your factorial family videos. I think that it would be interesting to see videos on the factorial (and the other types) of the imaginary number.

  • @SylComplexDimensional
    @SylComplexDimensional 6 ปีที่แล้ว +5

    The explicit approach is 🔥🔥🔥🎅🏾

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว +3

      Sylvester Cleveland thank you!!!!

  • @kiiometric
    @kiiometric 6 ปีที่แล้ว

    I love your videos! I think you're underrated in youtube, you should get much more likes for that amazing stuff

  • @chinmayasahu5577
    @chinmayasahu5577 6 ปีที่แล้ว +5

    I feel so dumb and so smart at the same time

  • @ChrisAsHell
    @ChrisAsHell 5 ปีที่แล้ว +2

    But is impossible that just two out of three get their gifts back... If they did, the third one also did

  • @codyhintz7866
    @codyhintz7866 3 ปีที่แล้ว +2

    Toward the end you mention for big enough n you can use !n(about)=n!e^(-1) so how big does n have to be for this to apply?

    • @CarmenLC
      @CarmenLC 3 ปีที่แล้ว +2

      i know im late but for n = 5 its already only 1% off from 1/e (≈37%)
      !5 ≈ 5!/e to 3rd s.f.
      so big values are n > 4

  • @zubmit700
    @zubmit700 6 ปีที่แล้ว +1

    Love your videos and I'm not even studying math.

  • @proggenius2024
    @proggenius2024 ปีที่แล้ว

    this is a very nice video. thanks

  • @yrcmurthy8323
    @yrcmurthy8323 6 ปีที่แล้ว +2

    Sir, what is the relationship between subfactorial with hyperfactorial and Double factorial.

    • @yrcmurthy8323
      @yrcmurthy8323 6 ปีที่แล้ว

      Sir, even I had some limit questions I mailed you...

  • @HerbertLandei
    @HerbertLandei 6 ปีที่แล้ว +1

    How about a "deranged" version of the choose operator? dechoose(3,2) would mean "all possibilities for two people to choose from 3 gifts without getting their own"

  • @NonTwinBrothers
    @NonTwinBrothers 4 ปีที่แล้ว

    Christmassssss math time

  • @Ridwan-wm3is
    @Ridwan-wm3is 6 ปีที่แล้ว

    Poor octopus went into toxic shock...

  • @bjarnivalur6330
    @bjarnivalur6330 6 ปีที่แล้ว +5

    Hay! Do you make your videos for your students or just for fun? Or is there some other secret purpose behind them?

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว +4

      Bjarni Valur both!

    • @johnbohnenstiel605
      @johnbohnenstiel605 6 ปีที่แล้ว +1

      shouldn't it be 2 (choose) 1? @@blackpenredpen

    • @yrcmurthy8323
      @yrcmurthy8323 6 ปีที่แล้ว +1

      @@johnbohnenstiel605 yep dude, it's correct

    • @Apollorion
      @Apollorion 6 ปีที่แล้ว +1

      @@blackpenredpenIs that "both" an answer to Bjarni Valur's first question or the second?

  • @Nick-hc2cs
    @Nick-hc2cs 6 ปีที่แล้ว +3

    that means that e is equal to n!/!n

  • @ffggddss
    @ffggddss 4 ปีที่แล้ว

    Except for n = 0, you can write
    !n = {n!/e}
    where {x} is the *nearest* integer to x. In fact, the difference goes as
    !n - {n!/e} ~ (-1)ⁿ/(n+2)
    in the sense that the ratio of those two sides 1 as n ∞; and that it converges to 1 faster than any other term of the form a/(n+b).
    Fred
    PS. Somehow I missed this when it came out over a year & a half ago, but I'm glad I found it now. Next, I will check out its predecessor - the recursive approach.

  • @Patapom3
    @Patapom3 6 ปีที่แล้ว

    Amazing!

  • @apta9931
    @apta9931 6 ปีที่แล้ว +1

    Cool new intro

  • @10_01-i6b
    @10_01-i6b 6 ปีที่แล้ว

    what is i! in complex world?

  • @sugarfrosted2005
    @sugarfrosted2005 6 ปีที่แล้ว +1

    I was wondering if this divided factorial and it does.

  • @OneEyedJacker
    @OneEyedJacker 11 หลายเดือนก่อน

    Now I get it!

  • @przemysawkwiatkowski2674
    @przemysawkwiatkowski2674 6 ปีที่แล้ว

    Actually how good is the approximation n!/e ?

  • @angelmendez-rivera351
    @angelmendez-rivera351 6 ปีที่แล้ว +2

    This is good stuff! Now to generalize this using the Incomplete Gamma function, or just good old Gamma function?

  • @CalamityInAction
    @CalamityInAction 6 ปีที่แล้ว

    I like the new intro. :)

  • @clubstepdj
    @clubstepdj 6 ปีที่แล้ว

    I still don't get it
    Is it ok if the 3rd person gets his own gift (gift C) as a gift?
    Is it "all 3 of us cannot get the same gift" or "only i can't get my own gift, screw with others"?

  • @OtiumAbscondita
    @OtiumAbscondita 6 ปีที่แล้ว +2

    who made the intro?

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว

      a subscriber

    • @OtiumAbscondita
      @OtiumAbscondita 6 ปีที่แล้ว

      blackpenredpen ok but look at my comment on your 2 latest videos...

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว

      Mathedidasko
      I did and I replied.

  • @kedarsalunkhe1142
    @kedarsalunkhe1142 6 ปีที่แล้ว +2

    R u using inclusion exclusion principle?

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว +1

      Yes. I forgot if I mentioned in the video or not.

    • @kedarsalunkhe1142
      @kedarsalunkhe1142 6 ปีที่แล้ว

      blackpenredpen thank you sir

    • @ThePharphis
      @ThePharphis 6 ปีที่แล้ว

      you did mention it in the video, btw

  • @askyle
    @askyle 6 ปีที่แล้ว

    At the last bit i thought you were also gonna plug the Stirling approximation ._.

  • @yoavcarmel1245
    @yoavcarmel1245 6 ปีที่แล้ว +2

    for any real number x*
    13:35

  • @blue_blue-1
    @blue_blue-1 6 ปีที่แล้ว +1

    I am looking like the octopus in the thumbnail. Yes, I admit not having understood the explanation about the sample space.
    Edit: In my previous note I mixed up the n‘s at the end.

  • @zaidsalameh1
    @zaidsalameh1 6 ปีที่แล้ว

    Dude can you do a series about Wheels theory

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว

      ZAID SALAMEH that looks really cool. I will look into it.

    • @zaidsalameh1
      @zaidsalameh1 6 ปีที่แล้ว

      Thanks dude!!

  • @Methylshift
    @Methylshift 6 ปีที่แล้ว

    cool intro!

  • @rodbhar6522
    @rodbhar6522 6 ปีที่แล้ว

    So "Isn't it?" is gone, but "Well well" is here. Can't we have both?

  • @lucazara9137
    @lucazara9137 6 ปีที่แล้ว

    So the limit x->infinity of x! / !x is e

  • @owem6511
    @owem6511 6 ปีที่แล้ว +1

    1C2= 1/2 confirmed

    • @blacker4404
      @blacker4404 6 ปีที่แล้ว

      Nope.
      1C2 = 2.

    • @blacker4404
      @blacker4404 6 ปีที่แล้ว

      Oh, nvm. I thought you meant 2C1.

  • @pituitlechat3807
    @pituitlechat3807 6 ปีที่แล้ว

    yeah! a prove that Christmas is real!

  • @i_am_anxious02
    @i_am_anxious02 6 ปีที่แล้ว +1

    Black Pen Red Pen->
    Someone asked this and I wanna know, but ima put my own spin on it;
    Could !n! Be H(n) (hyperfactorial)?

    • @yrcmurthy8323
      @yrcmurthy8323 6 ปีที่แล้ว +1

      No, my friend

    • @yrcmurthy8323
      @yrcmurthy8323 6 ปีที่แล้ว +1

      I checked

    • @i_am_anxious02
      @i_am_anxious02 6 ปีที่แล้ว

      Yrc Murthy oh I see how it is... I mean, we always say Sin^-1(x) for inverse sin(x), but that should mean 1/(Sin(x)), you can use notation in other ways, but fine...

    • @yrcmurthy8323
      @yrcmurthy8323 6 ปีที่แล้ว

      @@i_am_anxious02 Yes exactly !, my friend. Arcsine function cannot be written as In the denominator.
      i.e.lets assume we don't know if it is true. if it is true what you said, then let us take theta = 45 deg. Let's assume we don't know theta. sin(45 degrees) = 1/√2 and theta = x
      arcsin(1/√2) = x
      1/sin(1/√2) = x
      Then sinx = 1/√2
      Then again it continues.
      But finally x = theta = 45 degrees.

    • @i_am_anxious02
      @i_am_anxious02 6 ปีที่แล้ว

      Yrc Murthy we know, it’s just the notation. Not all notation follows your exact expectations all the time. You saying it can’t be written in the denominator only helps Emmy case, because the notations works a little different, so why not apply this here and say !n! = H(n)? I might sound idiotic, and correct me if I’m wrong, but arcsin(x) = Sin^(-1)(x), but this isn’t equal to the typical -1 power, sometimes notation doesn’t work like you think.

  • @btdpro752
    @btdpro752 6 ปีที่แล้ว +2

    Hi

  • @AndDiracisHisProphet
    @AndDiracisHisProphet 6 ปีที่แล้ว

    11:25 that's why my wishes never come true -.-

  • @brooksgunn5235
    @brooksgunn5235 6 ปีที่แล้ว

    _Peep that intro!_

  • @choltiabdenour8326
    @choltiabdenour8326 6 ปีที่แล้ว +1

    Plz..... I Need How To Be Cool In InteGrale

  • @hamsterdam1942
    @hamsterdam1942 6 ปีที่แล้ว

    I see in ur intro discontinuous montage ;о

  • @rmela4501
    @rmela4501 6 ปีที่แล้ว +2

    Can !n! Be defined?

    • @origamikatakana
      @origamikatakana 6 ปีที่แล้ว +1

      (!n)! or !(n!)? And both should work just fine.

    • @stevethecatcouch6532
      @stevethecatcouch6532 6 ปีที่แล้ว +3

      Yes. But we have to decide whether !n! = !(n!) or !n! = (!n)!? Using a left to right convention, !n! would equal (!n)!.

    • @i_am_anxious02
      @i_am_anxious02 6 ปีที่แล้ว

      Steve the Cat Couch but the thing is, by that logic, !n=1(!n)=1!n=1n=n. This could be an entirely new notation instead...

    • @stevethecatcouch6532
      @stevethecatcouch6532 6 ปีที่แล้ว +1

      @@i_am_anxious02 Huh? How do you go from 1(!n) to 1!n? The whole point of the parentheses is to show that the ! goes with the n, not the 1.

    • @i_am_anxious02
      @i_am_anxious02 6 ปีที่แล้ว

      Steve the Cat Couch I’m being serious when I say that was a test, I wanted you to say this

  • @quantumsoul3495
    @quantumsoul3495 4 ปีที่แล้ว

    A 4 person Venn diagram is impossible because 4 is not prime

  • @yunfeichen9255
    @yunfeichen9255 4 ปีที่แล้ว

    Wow even linus is sponsered by honey huh??

  • @benwiley6512
    @benwiley6512 3 ปีที่แล้ว

    INTRO

  • @gouravmadhwal5548
    @gouravmadhwal5548 6 ปีที่แล้ว +3

    Plz integrate
    ln(ln(ln(lnx)))

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว +2

      Gourav Madhwal
      More ln please.

    • @gouravmadhwal5548
      @gouravmadhwal5548 6 ปีที่แล้ว +1

      @@blackpenredpen blackpenredpen btw..
      I really have one😅😅
      Plz integrate
      1
      -------------------------------
      ln(. 1
      ---------------------------
      ln(. 1
      ----------------------
      ln(. 1
      ------------------
      ln(x)))

    • @blackpenredpen
      @blackpenredpen  6 ปีที่แล้ว +2

      Gourav Madhwal
      That's it? That's too easy.
      When I was your age, I was able to integral x$^x$, where $ is a version of the superfacorial. I am currently working on #x^#x for my ph.D.

    • @gouravmadhwal5548
      @gouravmadhwal5548 6 ปีที่แล้ว +1

      @@blackpenredpen I know that's easy for you.....but not for me...we have limited mathematical learning here till 12th standard....but I love maths...specially calculus...therefore I watch your videos....gain something from them...that's why I keep asking questions from you using the comment section....you remember that question?...0 to 2π cos(sinx)•e^cosx...that question was asked by me only...from another youtube account😅😅....therefore plz integrate ln(ln(ln(lnx))) and
      1
      -------------------------------
      ln(. 1
      ---------------------------
      ln(. 1
      ----------------------
      ln(. 1
      ------------------
      ln(x)))

    • @jessehammer123
      @jessehammer123 6 ปีที่แล้ว +2

      blackpenredpen Primorials? I love primorials!

  • @maginobionrequiem9167
    @maginobionrequiem9167 6 ปีที่แล้ว

    Find x in x = 3+x

  • @Blue-jk4fw
    @Blue-jk4fw 6 ปีที่แล้ว

    !4=9 thank me later

    • @angelmendez-rivera351
      @angelmendez-rivera351 6 ปีที่แล้ว

      Aden Tate The incomplete Gamma function is more rigorous.

    • @angelmendez-rivera351
      @angelmendez-rivera351 6 ปีที่แล้ว

      Aden Tate The incomplete Gamma function should still work

  • @rockapedra1130
    @rockapedra1130 2 ปีที่แล้ว

    This is cool. Never heard of !n before