A141763 Column 3 of triangle A141760.

1, 1, 4, 23, 175, 1678, 19579, 270683, 4342447, 79498622, 1638471038, 37592670383, 951214496814, 26333793485772, 792232525678756, 25747819699179668, 899388184082559576, 33613386298645020835, 1338749843351681925409

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Formula

G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n/(1+x)^{(n+2)*(n+3)/2 - 3}.

a(n) = 1 - Sum_{j=0..n-1} a(j) * (-1)^(n-j) * C((j+2)(j+3)/2 + n-j-4, n-j) for n>0, with a(0)=1.

Prog

(PARI) {a(n)=if(n==0, 1, 1 - sum(j=0, n-1, a(j)*(-1)^(n-j)*binomial((j+2)*(j+3)/2-3+n-j-1, n-j)))}

Crossrefs

Cf. A141760, A141761, A141762, A141764.

Sequence in context: A328006 A127131 A083355 * A025550 A350669 A067545

Adjacent sequences: A141760 A141761 A141762 * A141764 A141765 A141766

Keyword

nonn

Author

Paul D. Hanna, Jul 18 2008

Status

approved