OFFSET
0,2
LINKS
Robert Israel, Table of n, a(n) for n = 0..523
FORMULA
O.g.f.: Sum_{n>=0} 2^n*x^n/(1 - (n+1)*x)^(n+1).
E.g.f.: exp(x + 2*x*exp(x)).
MAPLE
S:= series(exp(x+2*x*exp(x)), x, 51):
seq(coeff(S, x, j)*j!, j=0..50); # Robert Israel, Jan 20 2017
PROG
(PARI) {a(n)=sum(k=0, n, binomial(n, k)*2^k*(k+1)^(n-k))}
(PARI) {a(n)=polcoeff(sum(m=0, n, 2^m*x^m/(1-(m+1)*x+x*O(x^n))^(m+1)), n)}
(PARI) {a(n)=n!*polcoeff(exp(x+2*x*exp(x+x*O(x^n))), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 06 2011
STATUS
approved