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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A293299 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of e.g.f. Product_{i>0} 1/(Sum_{j=0..k} x^(j*i)/j!).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -1, 0, 0, 1, -1, -1, -6, 0, 1, -1, -1, 0, 24, 0, 1, -1, -1, -1, -6, -120, 0, 1, -1, -1, -1, 2, 30, 720, 0, 1, -1, -1, -1, 1, 10, 270, -5040, 0, 1, -1, -1, -1, 1, 20, 170, 0, 80640, 0, 1, -1, -1, -1, 1, 19, 140, 1050, 2520, -725760, 0, 1, -1
Offset: 0

Views

Author

Seiichi Manyama, Oct 05 2017

Keywords

Examples

			Square array begins:
   1,    1,  1,  1,  1, ...
   0,   -1, -1, -1, -1, ...
   0,    0, -1, -1, -1, ...
   0,   -6,  0, -1, -1, ...
   0,   24, -6,  2,  1, ...
   0, -120, 30, 10, 20, ...
		

Crossrefs

Columns k=0..1 give A000007, A293300.
Rows n=0 gives A000012.
Main diagonal gives A293116.

A293487 E.g.f.: Product_{m>0} (1 + x^(2*m-1)).

Original entry on oeis.org

1, 1, 0, 6, 24, 120, 720, 5040, 80640, 725760, 7257600, 79833600, 1437004800, 18681062400, 261534873600, 5230697472000, 104613949440000, 1778437140480000, 32011868528640000, 729870602452992000, 17030314057236480000, 408727537373675520000, 8992005822220861440000
Offset: 0

Views

Author

Seiichi Manyama, Oct 10 2017

Keywords

Crossrefs

Column k=1 of A293486.

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1 + x^(2*k-1), {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, 20]! (* Vaclav Kotesovec, Oct 15 2017 *)
  • PARI
    N=66; x='x+O('x^N); Vec(serlaplace(prod(m=1, N, 1+x^(2*m-1))))

Formula

a(n) = n! * A000700(n).
a(n) ~ sqrt(Pi) * exp(Pi*sqrt(n/6) - n) * n^(n - 1/4) / (2^(5/4) * 3^(1/4)). - Vaclav Kotesovec, Oct 15 2017
Showing 1-2 of 2 results.