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.

Showing 1-2 of 2 results.

A291980 Triangle read by rows, T(n, k) = n!*[t^k] ([x^n] exp(x*t)/(1 - log(1+x))) for 0<=k<=n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 2, 3, 3, 1, 4, 8, 6, 4, 1, 14, 20, 20, 10, 5, 1, 38, 84, 60, 40, 15, 6, 1, 216, 266, 294, 140, 70, 21, 7, 1, 600, 1728, 1064, 784, 280, 112, 28, 8, 1, 6240, 5400, 7776, 3192, 1764, 504, 168, 36, 9, 1
Offset: 0

Views

Author

Peter Luschny, Sep 15 2017

Keywords

Examples

			Triangle starts:
[1]
[1,      1]
[1,      2,    1]
[2,      3,    3,   1]
[4,      8,    6,   4,   1]
[14,    20,   20,  10,   5,   1]
[38,    84,   60,  40,  15,   6,  1]
[216,  266,  294, 140,  70,  21,  7, 1]
[600, 1728, 1064, 784, 280, 112, 28, 8, 1]
		

Crossrefs

Row sums: A291981.
Columns: A006252 (c=1), A108125 (c=2).
Diagonals: A000217 (d=3), A007290 (d=4), A033488 (d=5).
Cf. A291978.

Programs

  • Maple
    T_row := proc(n) exp(x*t)/(1 - log(1+x)): series(%, x, n+1):
    seq(n!*coeff(coeff(%,x,n), t, k), k=0..n) end:
    seq(T_row(n), n=0..10);
  • Mathematica
    T[n_, k_] := Binomial[n, n - k]*Sum[j!*StirlingS1[n - k, j], {j, 0, n - k}]; Flatten[Table[T[n, k], {n, 0, 9}, {k, 0, n}]] (* Detlef Meya, May 12 2024 *)

Formula

T(n, k) = binomial(n, n - k)*Sum_{j=0..n - k} j!*Stirling1(n - k, j). - Detlef Meya, May 12 2024

A355719 Expansion of e.g.f. exp( x/(1 - log(1+x)) ).

Original entry on oeis.org

1, 1, 3, 10, 45, 231, 1405, 9472, 72177, 596845, 5442631, 53052726, 561826309, 6286949787, 75704999721, 954108249676, 12862823623393, 179921659771257, 2683989118991467, 41178997678745506, 673670267643931581, 11223738258484213519, 200027545794685345749
Offset: 0

Views

Author

Seiichi Manyama, Jul 15 2022

Keywords

Comments

a(43) is negative. - Vaclav Kotesovec, Jul 15 2022

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x/(1-log(1+x)))))
    
  • PARI
    a006252(n) = sum(k=0, n, k!*stirling(n, k, 1));
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, j*a006252(j-1)*binomial(i-1, j-1)*v[i-j+1])); v;

Formula

a(0) = 1; a(n) = Sum_{k=1..n} A108125(k) * binomial(n-1,k-1) * a(n-k).
Showing 1-2 of 2 results.