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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A362019 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = (-1)^n * Sum_{j=0..n} (-k*j)^j * binomial(n,j).

Original entry on oeis.org

1, 1, -1, 1, 0, 1, 1, 1, 3, -1, 1, 2, 13, 17, 1, 1, 3, 31, 173, 169, -1, 1, 4, 57, 629, 3321, 2079, 1, 1, 5, 91, 1547, 18025, 81529, 31261, -1, 1, 6, 133, 3089, 58993, 662639, 2443333, 554483, 1, 1, 7, 183, 5417, 147081, 2888979, 29752957, 86475493, 11336753, -1
Offset: 0

Views

Author

Seiichi Manyama, May 05 2023

Keywords

Examples

			Square array begins:
   1,    1,     1,      1,       1,       1, ...
  -1,    0,     1,      2,       3,       4, ...
   1,    3,    13,     31,      57,      91, ...
  -1,   17,   173,    629,    1547,    3089, ...
   1,  169,  3321,  18025,   58993,  147081, ...
  -1, 2079, 81529, 662639, 2888979, 8998399, ...
		

Crossrefs

Columns k=0..3 give A033999, (-1)^n * A069856(n), A362859, A362860.
Main diagonal gives A362862.
Cf. A362856.

Programs

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

Formula

E.g.f. of column k: exp(-x) / (1 + LambertW(-k*x)).
G.f. of column k: Sum_{j>=0} (k*j*x)^j / (1 + x)^(j+1).

A362857 Expansion of e.g.f. exp(-2*x) / (1 + LambertW(-x)).

Original entry on oeis.org

1, -1, 4, 7, 120, 1373, 21028, 373931, 7670736, 178064281, 4615519884, 132139421423, 4141235867992, 141016013784917, 5184372688776180, 204668397165154867, 8635388122600110240, 387787185320578895537, 18467131524896950511644
Offset: 0

Views

Author

Seiichi Manyama, May 05 2023

Keywords

Crossrefs

Column k=2 of A362856.
Cf. A362859.

Programs

  • Mathematica
    With[{nn=20},CoefficientList[Series[Exp[-2x]/(1+LambertW[-x]),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Aug 26 2023 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-2*x)/(1 + lambertw(-x))))

Formula

G.f.: Sum_{k>=0} (k*x)^k / (1 + 2*x)^(k+1).
a(n) = Sum_{k=0..n} (-2)^(n-k) * k^k * binomial(n,k).
a(n) ~ exp(-2*exp(-1)) * n^n. - Vaclav Kotesovec, Aug 05 2025
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