A171207 G.f. satisfies: A(x) = (1 + x*A(2x))^6.

1, 6, 87, 2468, 131799, 13400550, 2646848041, 1030386755856, 796631252763576, 1227659952939056640, 3777547269650299331856, 23228194648169000672639616, 285544368619000766118426358016, 7018967175754802830514246125923840, 345031382341287335424234252089128848384

Offset: 0

Author

Paul D. Hanna, Dec 05 2009

Keywords

• nonn

Crossrefs

Cf. A135868, A171200-A171205, A171206, A171208-A171211.

Programs

Mathematica

terms = 15; A[] = 0; Do[A[x] = (1+x*A[2x])^6 + 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))^6); polcoeff(A, n)}

Formula

Self-convolution 6th power of A171206 where a(n) = A171206(n+1)/2^n for n>=0.

Extensions

a(14) from Stefano Spezia, Apr 02 2025