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.

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A368765 a(n) = n! * (1 + Sum_{k=0..n} (-1)^k * k / k!).

Original entry on oeis.org

1, 0, 2, 3, 16, 75, 456, 3185, 25488, 229383, 2293840, 25232229, 302786760, 3936227867, 55107190152, 826607852265, 13225725636256, 224837335816335, 4047072044694048, 76894368849186893, 1537887376983737880, 32295634916658495459, 710503968166486900120, 16341591267829198702737
Offset: 0

Views

Author

Seiichi Manyama, Jan 04 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Table[n!(1+Sum[(-1)^k k/k!,{k,0,n}]),{n,0,30}] (* Harvey P. Dale, Mar 26 2025 *)
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace((1-x*exp(-x))/(1-x)))

Formula

a(0) = 1; a(n) = n*a(n-1) + (-1)^n * n.
a(n) = n! - A000240(n).
E.g.f.: (1 - x * exp(-x)) / (1-x).
a(n) ~ (1 - exp(-1)) * n!. - Vaclav Kotesovec, Jan 13 2024

A165813 a(n) = n*(a(n-1)+3), a(0)=1.

Original entry on oeis.org

1, 4, 14, 51, 216, 1095, 6588, 46137, 369120, 3322107, 33221100, 365432133, 4385185632, 57007413255, 798103785612, 11971556784225, 191544908547648, 3256263445310067, 58612742015581260, 1113642098296043997
Offset: 0

Views

Author

Philippe Deléham, Sep 28 2009

Keywords

Crossrefs

Programs

  • Mathematica
    FoldList[#1*#2 + 3 #2 &, 1, Range[19]] (* Robert G. Wilson v, Jul 07 2012 *)

Formula

a(n) = n! + 3*floor(e*n!) - 3. - Gary Detlefs, Jun 06 2010

A166677 a(n)= n*(a(n-1)+4), a(0)=1.

Original entry on oeis.org

1, 5, 18, 66, 280, 1420, 8544, 59836, 478720, 4308516, 43085200, 473937244, 5687246976, 73934210740, 1035078950416, 15526184256300, 248418948100864, 4223122117714756, 76016198118865680, 1444307764258447996
Offset: 0

Views

Author

Philippe Deléham, Oct 18 2009

Keywords

Crossrefs

Programs

  • Maple
    f:= gfun:-rectoproc({a(n)=n*(a(n-1)+4),a(0)=1},a(n),remember):
    map(f, [$0..30]); # Robert Israel, May 22 2016
  • Mathematica
    FoldList[#1*#2 + 4 #2 &, 1, Range[19]] (* Robert G. Wilson v, Jul 07 2012 *)

Formula

a(n) = n!+4*floor(e*n!)-4, n>0. [Gary Detlefs, Jun 06 2010]
From Robert Israel, May 22 2016: (Start)
a(n) = n!*(1 + Sum_{k=0..n-1} 4/k!) = n! + 4 e n Gamma(n,1).
E.g.f.: (1+4*x*exp(x))/(1-x). (End)

A368759 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * (1 + Sum_{j=0..n} j^k/j!).

Original entry on oeis.org

2, 1, 3, 1, 2, 7, 1, 2, 6, 22, 1, 2, 8, 21, 89, 1, 2, 12, 33, 88, 446, 1, 2, 20, 63, 148, 445, 2677, 1, 2, 36, 141, 316, 765, 2676, 18740, 1, 2, 68, 351, 820, 1705, 4626, 18739, 149921, 1, 2, 132, 933, 2428, 4725, 10446, 32431, 149920, 1349290, 1, 2, 260, 2583, 7828, 15265, 29646, 73465, 259512, 1349289, 13492901
Offset: 0

Views

Author

Seiichi Manyama, Jan 04 2024

Keywords

Examples

			Square array begins:
     2,    1,    1,     1,     1,     1,      1, ...
     3,    2,    2,     2,     2,     2,      2, ...
     7,    6,    8,    12,    20,    36,     68, ...
    22,   21,   33,    63,   141,   351,    933, ...
    89,   88,  148,   316,   820,  2428,   7828, ...
   446,  445,  765,  1705,  4725, 15265,  54765, ...
  2677, 2676, 4626, 10446, 29646, 99366, 375246, ...
		

Crossrefs

Columns k=0..3 give A038159, A033540(n+1), A053817, A368760.
Cf. A337085.

Programs

  • PARI
    T(n, k) = n!*(1+sum(j=0, n, j^k/j!));

Formula

T(0,k) = 1 + 0^k and T(n,k) = n^k + n * T(n-1,k) for n>0.
T(n,k) = n! + A337085(n,k).
E.g.f. of column k: (1+ B_k(x) * exp(x)) / (1-x), where B_n(x) = Bell polynomials.
Previous Showing 11-14 of 14 results.