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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A361600 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..n} binomial(n+(k-1)*j,k*j)/j!.

Original entry on oeis.org

1, 1, 2, 1, 2, 5, 1, 2, 7, 16, 1, 2, 9, 34, 65, 1, 2, 11, 58, 209, 326, 1, 2, 13, 88, 473, 1546, 1957, 1, 2, 15, 124, 881, 4626, 13327, 13700, 1, 2, 17, 166, 1457, 10526, 52537, 130922, 109601, 1, 2, 19, 214, 2225, 20326, 145867, 677594, 1441729, 986410
Offset: 0

Views

Author

Seiichi Manyama, Mar 17 2023

Keywords

Examples

			Square array begins:
    1,    1,    1,     1,     1,     1, ...
    2,    2,    2,     2,     2,     2, ...
    5,    7,    9,    11,    13,    15, ...
   16,   34,   58,    88,   124,   166, ...
   65,  209,  473,   881,  1457,  2225, ...
  326, 1546, 4626, 10526, 20326, 35226, ...
		

Crossrefs

Columns k=0..3 give A000522, A002720, A361598, A361599.
Main diagonal gives A361607.
Cf. A293012.

Programs

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

Formula

E.g.f. of column k: exp( x/(1 - x)^k ) / (1-x).
T(n,k) = Sum_{j=0..n} (n+(k-1)*j)!/(k*j)! * binomial(n,j).

A361617 a(n) = n! * Sum_{k=0..n} binomial(n+(n-1)*(k+1),n-k)/k!.

Original entry on oeis.org

1, 2, 15, 214, 4721, 146046, 5958367, 307382090, 19459587009, 1478414285146, 132440451881231, 13787717744245182, 1647673524863409265, 223671725058601427414, 34184743554559413628191, 5837132027535188545269106, 1106136052471647285563082497
Offset: 0

Views

Author

Seiichi Manyama, Mar 18 2023

Keywords

Crossrefs

Main diagonal of A361616.
Cf. A361607.

Programs

  • PARI
    a(n) = n!*sum(k=0, n, binomial(n+(n-1)*(k+1), n-k)/k!);

Formula

a(n) = n! * [x^n] exp( x/(1-x)^n ) / (1-x)^n.
a(n) = Sum_{k=0..n} (n+(n-1)*(k+1))!/(n*k+n-1)! * binomial(n,k) for n > 0.
Showing 1-2 of 2 results.