A124835 Row sums of triangle A124834.

1, 2, 4, 9, 25, 91, 444, 2920, 25996, 314752, 5201874, 117719942, 3658433597, 156505343943, 9234365056453, 752841451059559, 84938741035295776, 13279814559055121447, 2880581923860441220144, 867855593621657824023139

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Formula

G.f.: A(x) = Sum_{k>=0} x^n * Product_{k=0..n} 1/(1 - binomial(n,k)*x).

Example

A(x) = 1/(1-x) + x/((1-x)(1-x)) + x^2/((1-x)(1-2x)(1-x)) + x^3/((1-x)(1-3x)(1-3x)(1-x)) + x^4/((1-x)(1-4x)(1-6x)(1-4x)(1-x)) +...

Prog

(PARI) {a(n)=sum(k=0, n, polcoeff(1/prod(j=0, k, 1-binomial(k, j)*x +x*O(x^n)), n-k))}

Crossrefs

Cf. A124834, A124836.

Sequence in context: A173496 A173311 A127055 * A125799 A220880 A307317

Adjacent sequences: A124832 A124833 A124834 * A124836 A124837 A124838

Keyword

nonn

Author

Paul D. Hanna, Nov 09 2006

Status

approved