OFFSET
0,3
FORMULA
a(n+1) = n!*Sum_{k=0..n} (k+1)/(n-k)!*a(k)*a(n-k). - Vladeta Jovovic, Jul 08 2008
EXAMPLE
O.g.f.: A(x) = 1 + x + 3*x^2 + 25*x^3 + 697*x^4 + 87261*x^5 + 63362851*x^6 +...
exp(x*A(x)) = 1 + x + 3*x^2/2! + 25*x^3/3! + 697*x^4/4! + 87261*x^5/5! + 63362851*x^6/6! +...
PROG
(PARI) {a(n)=local(E=1+x+x*O(x^n), F); for(j=0, n, F=exp(x*E); E=sum(i=0, n, polcoeff(F, i)*i!*x^i)); polcoeff(E, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 27 2007
STATUS
approved