A088694 E.g.f: A(x) = f(x*A(x)^3), where f(x) = (1+4*x)*exp(x).

1, 5, 159, 10228, 1009253, 135069696, 22882888555, 4696799559488, 1133128780421385, 314294095403352064, 98550149514670698071, 34473870245560804316160, 13310522831484403851847981, 5622806397207798234900070400, 2579680348909056700728913816227

Offset

0,2

Comments

Radius of convergence of A(x): r = (3^2/4^4)*exp(-1/4) = 0.0273797..., where A(r) = (4/3)*exp(1/12) and r = limit a(n)/a(n+1)*(n+1) as n->infinity. Radius of convergence is from a general formula yet unproved.

Links

Table of n, a(n) for n=0..14.

Formula

a(n) = n! * [x^n] ((1+4*x)*exp(x))^(3*n+1)/(3*n+1).

a(n) ~ 16^(2*n+1) * n^(n-1) / (sqrt(13) * 9^(n+1) * exp(3*n/4 - 1/12)). - Vaclav Kotesovec, Jan 24 2014

Mathematica

Table[n!*SeriesCoefficient[((1+4*x)*E^x)^(3*n+1)/(3*n+1), {x, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Jan 24 2014 *)

Prog

(PARI) a(n)=n!*polcoeff(((1+4*x)*exp(x))^(3*n+1)+x*O(x^n), n, x)/(3*n+1)

Crossrefs

Cf. A088690, A088692, A088693.

Sequence in context: A321529 A156486 A208170 * A208583 A197310 A266525

Adjacent sequences: A088691 A088692 A088693 * A088695 A088696 A088697

Keyword

nonn

Author

Paul D. Hanna, Oct 07 2003

Status

approved