OFFSET
0,4
EXAMPLE
G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 4*x^4 + 9*x^5 + 22*x^6 + 55*x^7 +...
where
log(A(x)) = x + A(x)^2/A(x^2)*x^2/2 + A(x)^3/A(x^3)*x^3/3 + A(x)^4/A(x^4)*x^4/4 +...
more explicitly,
log(A(x)) = x + x^2/2 + 4*x^3/3 + 9*x^4/4 + 26*x^5/5 + 76*x^6/6 + 218*x^7/7 +...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, (A+x*O(x^n))^m/subst(A, x, x^m+x*O(x^n))*x^m/m))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 26 2011
STATUS
approved