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 1-3 of 3 results.

A351433 a(n) = n! * [x^n] 1/(1 + f^n(x)), where f(x) = exp(x) - 1.

Original entry on oeis.org

1, -1, 0, 0, -2, -75, -3334, -192864, -14443260, -1372372623, -162009663365, -23314158802286, -4022712394579207, -820399656345934444, -195326656416326556562, -53709209673236813446542, -16896296201917398543629108, -6030879950631118091070849321
Offset: 0

Views

Author

Seiichi Manyama, Feb 11 2022

Keywords

Crossrefs

Main diagonal of A351429.

Programs

  • Maple
    g:= x-> exp(x)-1:
    a:= n-> n! * coeff(series(1/(1+(g@@n)(x)), x, n+1), x, n):
    seq(a(n), n=0..22);  # Alois P. Heinz, Feb 11 2022
  • Mathematica
    T[n_, 0] := (-1)^n * n!; T[n_, k_] := T[n, k] = Sum[StirlingS2[n, j]*T[j, k - 1], {j, 0, n}]; a[n_] := T[n, n]; Array[a, 17, 0] (* Amiram Eldar, Feb 11 2022 *)
  • PARI
    T(n, k) = if(k==0, (-1)^n*n!, sum(j=0, n, stirling(n, j, 2)*T(j, k-1)));
    a(n) = T(n, n);

Formula

a(n) = T(n,n), T(n,k) = Sum_{j=0..n} Stirling2(n,j) * T(j,k-1), k>1, T(n,0) = (-1)^n * n!.

A111933 Triangle read by rows, generated from Stirling cycle numbers.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 7, 6, 1, 4, 15, 35, 24, 1, 5, 26, 105, 228, 120, 1, 6, 40, 234, 947, 1834, 720, 1, 7, 57, 440, 2696, 10472, 17582, 5040, 1, 8, 77, 741, 6170, 37919, 137337, 195866, 40320, 1, 9, 100, 1155, 12244, 105315, 630521, 2085605, 2487832, 362880
Offset: 1

Views

Author

Gary W. Adamson, Aug 21 2005

Keywords

Comments

Let M = the infinite lower triangular matrix of Stirling cycle numbers (A008275). Perform M^n * [1, 0, 0, 0, ...] forming an array. Antidiagonals of that array become the rows of this triangle.

Examples

			Row 5 of the triangle = 1, 4, 15, 35, 24; generated from M^n * [1,0,0,0,...] (n = 1 through 5); then take antidiagonals.
Terms in the array, first few rows are:
  1, 1,  2,   6,    24,    120, ...
  1, 2,  7,  35,   228,   1834, ...
  1, 3, 15, 105,   947,  10472, ...
  1, 4, 26, 234,  2697,  37919, ...
  1, 5, 40, 440,  6170, 105315, ...
  1, 6, 57, 741, 12244, 245755, ...
  ...
First few rows of the triangle are:
  1;
  1, 1;
  1, 2,  2;
  1, 3,  7,   6;
  1, 4, 15,  35,  24;
  1, 5, 26, 105, 228,  120;
  1, 6, 40, 234, 947, 1834, 720;
  ...
		

Crossrefs

Column 3 of the array = A005449.
Column 4 of the array = A094952.

Extensions

a(28), a(36) and a(45) corrected by Seiichi Manyama, Feb 11 2022

A351424 a(n) = n! * [x^n] -log(1 - f^(n-1)(x)), where f(x) = log(1+x).

Original entry on oeis.org

1, 0, 3, -48, 1270, -50375, 2803829, -208616562, 20003317746, -2402323535658, 353219463307920, -62411008199372327, 13048469028962425266, -3186116313706825820802, 898478811755719496052919, -289795933163271680910773018, 106008143082108931457543700504
Offset: 1

Views

Author

Seiichi Manyama, Feb 11 2022

Keywords

Crossrefs

Main diagonal of A351420.

Programs

  • Maple
    g:= x-> log(1+x):
    a:= n-> n! * coeff(series(-log(1-(g@@(n-1))(x)), x, n+1), x, n):
    seq(a(n), n=1..19);  # Alois P. Heinz, Feb 11 2022
  • Mathematica
    T[n_, 1] := (n - 1)!; T[n_, k_] := T[n, k] = Sum[StirlingS1[n, j] * T[j, k - 1], {j, 1, n}]; a[n_] := T[n, n]; Array[a, 16] (* Amiram Eldar, Feb 11 2022 *)
  • PARI
    T(n, k) = if(k==1, (n-1)!, sum(j=1, n, stirling(n, j, 1)*T(j, k-1)));
    a(n) = T(n, n);

Formula

a(n) = T(n,n), T(n,k) = Sum_{j=1..n} Stirling1(n,j) * T(j,k-1), k>1, T(n,1) = (n-1)!.
Showing 1-3 of 3 results.