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.

A306173 a(n) is the n-th term of the inverse Euler transform of j-> n^(j-1).

Original entry on oeis.org

1, 1, 6, 42, 420, 5155, 77658, 1376340, 28133616, 651317463, 16846515510, 481472570920, 15067838554860, 512473599799551, 18821719654854998, 742395982266536520, 31299550394528466960, 1404629090174946183156, 66851805805525048040334, 3363381327122496643643628
Offset: 1

Views

Author

Alois P. Heinz, Jun 23 2018

Keywords

Crossrefs

Main diagonal of A065177.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(g(i, k)+j-1, j)*b(n-i*j, i-1,k), j=0..n/i)))
        end:
    g:= proc(n, k) option remember; k^(n-1)-b(n, n-1, k) end:
    a:= n-> g(n$2):
    seq(a(n), n=1..21);
  • Mathematica
    b[n_, i_, k_] := b[n, i, k] = If[n == 0, 1, If[i < 1, 0, Sum[Binomial[g[i, k] + j - 1, j]*b[n - i*j, i - 1, k], {j, 0, n/i}]]];
    g[n_, k_] := g[n, k] = k^(n - 1) - b[n, n - 1, k];
    a[n_] := g[n, n];
    a /@ Range[21] (* Jean-François Alcover, Jan 06 2020, after Alois P. Heinz *)

Formula

a(n) ~ (1 - exp(-1)) * n^(n-1). - Vaclav Kotesovec, Oct 08 2019

A383033 Square array A(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where A(n,k) is the n-th term of the inverse Weigh transform of j-> k^(j-1).

Original entry on oeis.org

1, 1, 1, 1, 2, 0, 1, 3, 2, 1, 1, 4, 6, 5, 0, 1, 5, 12, 18, 6, 0, 1, 6, 20, 46, 42, 11, 0, 1, 7, 30, 95, 156, 113, 18, 1, 1, 8, 42, 171, 420, 566, 294, 35, 0, 1, 9, 56, 280, 930, 1930, 2028, 798, 56, 0, 1, 10, 72, 428, 1806, 5185, 8820, 7396, 2128, 105, 0
Offset: 1

Views

Author

Seiichi Manyama, Apr 13 2025

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,    1,     1,     1, ...
  1,  2,   3,    4,    5,     6,     7, ...
  0,  2,   6,   12,   20,    30,    42, ...
  1,  5,  18,   46,   95,   171,   280, ...
  0,  6,  42,  156,  420,   930,  1806, ...
  0, 11, 113,  566, 1930,  5185, 11851, ...
  0, 18, 294, 2028, 8820, 28830, 77658, ...
		

Crossrefs

Columns k=1..3 give A209229, A383034, A383035.
Main diagonal gives A316073.
Cf. A383023.

Formula

A(n,k) = (1/n) * (k^n - (k-1)^n + Sum_{d
A(n,k) = A383023(n,k) - A383023(n,k-1).
Product_{n>=1} (1 + x^n)^A(n,k) = (1 - (k-1)*x)/(1 - k*x).
Showing 1-2 of 2 results.