A135868 G.f. A(x) = (1 + x*A(2*x))^2.

1, 2, 9, 80, 1368, 45344, 2952208, 381005824, 97928967168, 50238812700672, 51495089926791168, 105513593089512439808, 432289346894817079853056, 3541746937174189008054386688, 58031524865557213409213540204544, 1901635048957282075182110362797342720, 124627456377710926240825658971690792648704

Offset: 0

Author

Paul D. Hanna, Dec 02 2007

Keywords

• nonn

Comments

Self-convolution of A135867 such that A135867(n+1) = 2^n*a(n).

Crossrefs

Cf. A135867.

Programs

Mathematica

terms = 17; A[] = 0; Do[A[x] = (1 + x*A[2x])^2 + 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)^2);polcoeff(A^2,n)}

Extensions

a(15)-a(16) from Stefano Spezia, Apr 02 2025