A205772 G.f. satisfies: A(x) = 1/Product_{n>=1} (1 - 2*x^n*A(x^n)).

1, 2, 10, 50, 290, 1766, 11442, 76522, 526574, 3697722, 26403186, 191072922, 1398344838, 10330855286, 76945148882, 577135722754, 4355579825058, 33050011129198, 251996066644866, 1929712025078322, 14834772898730766, 114445491235869774

Offset

0,2

Links

Table of n, a(n) for n=0..21.

Example

G.f.: A(x) = 1 + 2*x + 10*x^2 + 50*x^3 + 290*x^4 + 1766*x^5 +...,
where A(x) = 1/((1 - 2*x*A(x)) * (1 - 2*x^2*A(x^2)) * (1 - 2*x^3*A(x^3)) * ...).

Prog

(PARI) {a(n)=local(A=1+x); for(i=1, n, A=1/prod(k=1, n, (1-2*x^k*subst(A, x, x^k+x*O(x^n))))); polcoeff(A, n)}

Crossrefs

Cf. A050383, A196192, A205773.

Sequence in context: A206637 A318494 A020088 * A306336 A074140 A128449

Adjacent sequences: A205769 A205770 A205771 * A205773 A205774 A205775

Keyword

nonn

Author

Paul D. Hanna, Jan 31 2012

Status

approved