A171203 G.f. satisfies: A(x) = (1 + x*A(2x))^4.

1, 4, 38, 708, 24961, 1682688, 220959136, 57266675520, 29497077110720, 30294634141775360, 62134850895148484608, 254691311135373319017472, 2087196424913845641682560512, 34202892422993270952623113994240, 1120863025258656246362522776511881216, 73460242428855296330451249854756580540416

Offset: 0

Author

Paul D. Hanna, Dec 05 2009

Keywords

• nonn

Crossrefs

Cf. A135868, A171200, A171201, A171202, A171204-A171211.

Programs

Mathematica

terms = 16; A[] = 0; Do[A[x] = (1 + x*A[2x])^4 + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* Stefano Spezia, Apr 02 2025 *)

PARI

{a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=(1+x*subst(A, x, 2*x))^4); polcoeff(A, n)}

Formula

Self-convolution 4th power of A171202 where a(n) = A171202(n+1)/2^n for n>=0.

Extensions

a(14)-a(15) from Stefano Spezia, Apr 02 2025