OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..77
FORMULA
a(n) ~ c * n! * 2^(n*(n-1)/2), where c = 1.429815286617205023097354008... - Vaclav Kotesovec, Feb 22 2014
EXAMPLE
G.f.: A(x) = 1 + x + 4*x^2 + 54*x^3 + 1928*x^4 + 164650*x^5 + 32676492*x^6 +...
PROG
(PARI) {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D} /* n-th derivative of F */
{a(n)=local(A=1+x+x*O(x^n)); for(i=1, n, A=1+sum(k=1, n, x^k/k!*Dx(k, x*A^k+x*O(x^n) ))); polcoeff(A, n)}
for(n=0, 20, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Apr 21 2012
STATUS
approved