A212273 a(n) = n * A000699(n).

1, 2, 12, 108, 1240, 16980, 267624, 4750872, 93615408, 2026018980, 47764893000, 1218621868200, 33459133580496, 983950866169544, 30862364045494800, 1028656519404191280, 36312294166359724128, 1353561646509338629572, 53133041579508472510728

Offset: 1

Author

Michael Somos, May 12 2012

Keywords

• nonn

Examples

			G.f. = x + 2*x^2 + 12*x^3 + 108*x^4 + 1240*x^5 + 16980*x^6 + 267624*x^7 + 4750872*x^8 + ...
		

Crossrefs

Cf. A000699, A178685.

Programs

PARI

{a(n) = my(A); A = O(x); for(i=1, n, A = x + A * (2 * x * A' - A)); n * polcoeff(A, n)};

Formula

a(n) = [x^n] A178685(x)^n.

a(n) ~ n^(n+1) * 2^(n+1/2) / exp(n+1). - Vaclav Kotesovec, Feb 22 2014