OFFSET
0,2
EXAMPLE
E.g.f.: A(x) = x^2/2! + 3*x^5/5! + 63*x^8/8! + 6804*x^11/11! + 1990170*x^14/14! + 1145276496*x^17/17! + 1172421884088*x^20/20! +...
where A'(x) = x + 3*x^4/4! + 63*x^7/7! + 6804*x^10/10! +...
and A(A(x)) = 3*x^4/4! + 63*x^7/7! + 6804*x^10/10! + 1990170*x^13/13! +...
PROG
(PARI) {a(n)=local(A=x^2/2); for(i=1, n, A=intformal(x+subst(A, x, A+O(x^(3*n+3))))); (3*n+2)!*polcoeff(A, 3*n+2)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 15 2011
STATUS
approved