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).

A368489 a(n) = Sum_{k=0..n} n^k * binomial(k+n,k).

Original entry on oeis.org

1, 3, 31, 643, 20421, 873806, 46994011, 3042431715, 230249448841, 19940350062394, 1944516598602711, 210829412453667998, 25156743053019602701, 3275876521195372322892, 462262670054775645538099, 70264375447526610838701091
Offset: 0

Views

Author

Seiichi Manyama, Dec 27 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n, n^k*binomial(k+n, k));

Formula

a(n) = [x^n] 1/((1-x) * (1-n*x)^(n+1)).
a(n) ~ 4^n * n^(n - 1/2) / sqrt(Pi). - Vaclav Kotesovec, Dec 27 2023
Showing 1-2 of 2 results.