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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A368487 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..n} k^j * binomial(j+k-1,j).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 5, 3, 1, 1, 10, 17, 4, 1, 1, 17, 64, 49, 5, 1, 1, 26, 177, 334, 129, 6, 1, 1, 37, 401, 1457, 1549, 321, 7, 1, 1, 50, 793, 4776, 10417, 6652, 769, 8, 1, 1, 65, 1422, 12889, 48526, 67761, 27064, 1793, 9, 1, 1, 82, 2369, 30234, 176185, 442276, 411825, 105796, 4097, 10, 1
Offset: 0

Views

Author

Seiichi Manyama, Dec 26 2023

Keywords

Examples

			Square array begins:
  1, 1,   1,    1,     1,      1, ...
  1, 2,   5,   10,    17,     26, ...
  1, 3,  17,   64,   177,    401, ...
  1, 4,  49,  334,  1457,   4776, ...
  1, 5, 129, 1549, 10417,  48526, ...
  1, 6, 321, 6652, 67761, 442276, ...
		

Crossrefs

Columns k=0..3 give A000012, A000027(n+1), A000337(n+1), A367591.
Main diagonal gives A368488.

Programs

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

Formula

G.f. of column k: 1/((1-x) * (1-k*x)^k).

A367592 Expansion of 1/((1-x) * (1-4*x)^3).

Original entry on oeis.org

1, 13, 109, 749, 4589, 26093, 140781, 730605, 3679725, 18097645, 87303661, 414459373, 1941186029, 8987616749, 41199871469, 187228759533, 844358755821, 3782116386285, 16838816966125, 74563177424365, 328550363440621, 1441256130749933, 6296699479008749
Offset: 0

Views

Author

Seiichi Manyama, Nov 24 2023

Keywords

Crossrefs

Partial sums of A038845.

Programs

  • Mathematica
    CoefficientList[Series[1/((1 - x)*(1 - 4*x)^3), {x, 0, 30}], x] (* Wesley Ivan Hurt, Aug 04 2025 *)
  • PARI
    a(n) = ((9*n^2+21*n+14)*4^(n+1)-2)/54;

Formula

G.f.: 1/((1-x) * (1-4*x)^3).
a(n) = ((9*n^2+21*n+14) * 4^(n+1) - 2)/54.
a(n) = 13*a(n-1) - 60*a(n-2) + 112*a(n-3) - 64*a(n-4). - Wesley Ivan Hurt, Aug 04 2025
Showing 1-2 of 2 results.