A171193 G.f. satisfies A(x) = 1/(1 - x*A(2x)^3).

1, 1, 7, 109, 3207, 174581, 17929279, 3559607005, 1389312382199, 1075527698708485, 1658535837898129263, 5105026337441341642861, 31395991691829167745766311, 385982564381552315528268500501

Offset

0,3

Links

Seiichi Manyama, Table of n, a(n) for n = 0..80

Formula

a(n) ~ c * 2^(n*(n-1)/2) * 3^n, where c = 0.80142677004566734464115933731029720165641... - Vaclav Kotesovec, Nov 03 2021

Mathematica

nmax = 15; A[_] = 0; Do[A[x_] = 1/(1 - x*A[2*x]^3) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] (* Vaclav Kotesovec, Nov 03 2021 *)

Prog

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1/(1-x*subst(A, x, 2*x)^3) ); polcoeff(A, n)}

Crossrefs

Cf. A015083, A171192, A171194-A171198.

Sequence in context: A371317 A303109 A101924 * A357393 A371315 A212371

Adjacent sequences: A171190 A171191 A171192 * A171194 A171195 A171196

Keyword

nonn

Author

Paul D. Hanna, Dec 05 2009

Status

approved