cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 11-15 of 15 results.

A136701 Final nonzero digit of n! in base 15.

Original entry on oeis.org

1, 1, 2, 6, 9, 8, 3, 6, 3, 12, 3, 3, 6, 3, 12, 12, 12, 9, 12, 3, 9, 9, 3, 9, 6, 9, 9, 3, 9, 6, 12, 12, 9, 12, 3, 12, 12, 9, 12, 3, 3, 3, 6, 3, 12, 6, 6, 12, 6, 9, 12, 12, 9, 12, 3, 6, 6, 12, 6, 9, 6, 6, 12, 6, 9, 9, 9, 3, 9, 6, 3, 3, 6, 3, 12, 9, 9, 3, 9, 6, 12, 12, 9, 12, 3, 12, 12, 9, 12, 3, 3, 3, 6
Offset: 0

Views

Author

Carl R. White, Jan 16 2008

Keywords

Comments

From Robert Israel, Jun 08 2018: (Start)
For n >= 6, a(n) is 3, 6, 9 or 12.
For k >= 2, a(5*k) = a(5*k+1) = a(5*k+3). (End)

Examples

			6! = 720 decimal = 330 quindecimal, so a(6) = 3.
		

Crossrefs

Programs

  • Maple
    a:= 1: b:= 0: R[0]:= 1:
    for n from 1 to 100 do
       alpha:= padic:-ordp(n,3);
       beta:= padic:-ordp(n,5);
       a:= a * n/3^alpha/5^beta;
       b:= b + alpha - beta;
       R[n]:= a * 3 &^ b mod 15;
    od:
    seq(R[n],n=0..100); # Robert Israel, Jun 08 2018
  • Mathematica
    nzd[x_]:=If[x[[-1,1]]==0,x[[-2,1]],x[[-1,1]]]; Table[nzd[Split[IntegerDigits[n!,15]]],{n,0,100}] (* Harvey P. Dale, Jul 11 2023 *)

A136693 Final nonzero digit of n! in base 6.

Original entry on oeis.org

1, 1, 2, 1, 4, 2, 2, 2, 4, 4, 4, 2, 4, 4, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 2, 4, 4, 2, 4, 4, 2, 2, 2, 4, 4, 4, 2, 4, 4, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 2, 2, 2, 4, 2, 2, 4, 4, 4, 2, 2, 2, 4, 2, 2, 4, 4, 4, 2, 4, 4, 2, 4, 4, 2, 2, 2, 4, 4, 4, 2, 4, 4, 2, 2, 2, 4, 4, 4, 2, 4, 4, 2, 2, 2, 4, 2
Offset: 0

Views

Author

Carl R. White, Jan 16 2008

Keywords

Examples

			6! = 720 decimal = 3200 senary, so a(6) = 2.
		

Crossrefs

Programs

  • Mathematica
    nzd6[n_]:=Module[{c=IntegerExponent[n!,6]},IntegerDigits[n!,6] [[-(c+1)]]]; Array[nzd6,100,0] (* Harvey P. Dale, Sep 02 2015 *)

A136700 Final nonzero digit of n! in base 14.

Original entry on oeis.org

1, 1, 2, 6, 10, 8, 6, 10, 10, 6, 4, 2, 10, 4, 4, 4, 8, 10, 12, 4, 10, 8, 8, 2, 6, 10, 8, 6, 12, 12, 10, 2, 8, 12, 2, 12, 12, 10, 2, 8, 12, 2, 6, 6, 12, 8, 4, 6, 8, 2, 2, 4, 12, 6, 2, 12, 6, 6, 12, 8, 4, 6, 8, 8, 8, 2, 6, 10, 8, 6, 2, 2, 4, 12, 6, 2, 12, 10, 10, 6, 4, 2, 10, 4, 10, 10, 6, 4, 2, 10, 4
Offset: 0

Views

Author

Carl R. White, Jan 16 2008

Keywords

Examples

			6! = 720 decimal = 396 quatridecimal, so a(6) = 6.
		

Crossrefs

A136766 a(n) = leading digit of n! in base 16.

Original entry on oeis.org

1, 1, 2, 6, 1, 7, 2, 1, 9, 5, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 5, 8, 12, 1, 2, 3, 6, 13, 1, 3, 6, 13, 1, 4, 9, 1, 3, 8, 1, 3, 10, 1, 4, 14, 2, 7, 1, 4, 14, 2, 9, 2, 7, 1, 5, 1, 4, 1, 4, 1, 3, 15, 4, 1, 4, 1, 5, 1, 6, 1, 7, 2, 10, 3, 15, 4, 1, 7, 2, 11, 3, 1, 6, 2, 11, 4, 1, 7, 2, 1, 5, 2, 12, 4, 1, 11
Offset: 0

Views

Author

Carl R. White, Jan 21 2008

Keywords

Examples

			For n=5, 5! = 5*4*3*2*1 = 120 in base 10, which is 78 in hexadecimal (7*16 + 8*1), so a(5) = 7. - _Michael B. Porter_, Sep 20 2016
		

Crossrefs

Programs

  • Mathematica
    Array[ IntegerDigits[#!, 16][[1]] &, 1001, 0] (* Robert G. Wilson v, Sep 20 2016 *)
    Table[Floor[#/16^Floor@ Log[16, #]] &[n!], {n, 0, 98}] (* Michael De Vlieger, Sep 20 2016 *)
  • PARI
    a(n) = digits(n!, 16)[1]; \\ Michel Marcus, Jan 27 2015

A136774 n! never ends in this many 0's in base 16.

Original entry on oeis.org

62, 94, 110, 118, 126, 158, 174, 182, 190, 206, 214, 222, 230, 238, 254, 286, 302, 310, 318, 334, 342, 350, 358, 366, 382, 398, 406, 414, 422, 430, 446, 454, 462, 478, 510, 542, 558, 566, 574, 590, 598, 606, 614, 622, 638, 654, 662, 670, 678, 686, 702, 710
Offset: 1

Views

Author

Carl R. White, Jan 21 2008

Keywords

Crossrefs

Programs

  • PARI
    is(n)=my(t=4*n+2,s=1-hammingweight(n)); while(s<0, s+=valuation(t+=2,2)); s>3 \\ Charles R Greathouse IV, Sep 22 2016

Formula

Conjecture: a(n) ~ 16n. This holds with probability 1 in a random model. - Charles R Greathouse IV, Sep 22 2016
Previous Showing 11-15 of 15 results.