0,3
Table of n, a(n) for n=0..12.
G.f.: A(x) = (1/x)*Series_Reversion(x/F(x)) where F(x) = Sum_{n>=0} x^n/sf(n) and sf(n) = Product_{k=0..n} k!.
G.f.: A(x) = 1 + x + 3*x^2/(1!*2!) + 31*x^3/(1!*2!*3!) + 1393*x^4/(1!*2!*3!*4!) + 330361*x^5/(1!*2!*3!*4!*5!) + 488337121*x^6/(1!*2!*3!*4!*5!*6!) +...
where
A(x) = 1 + x*A(x) + x^2*A(x)^2/(1!*2!) + x^3*A(x)^3/(1!*2!*3!) + x^4*A(x)^4/(1!*2!*3!*4!) +...
(PARI) {a(n)=local(F=sum(m=0, n, x^m/prod(k=0, m, k!)+x*O(x^n))); prod(k=0, n, k!)*polcoeff(1/x*serreverse(x/F), n)}
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=sum(m=0, n, x^m*(A+x*O(x^n))^m/prod(k=0, m, k!))); prod(k=0, n, k!)*polcoeff(A, n)}
Cf. A000178.
Sequence in context: A319253 A328811 A136584 * A141153 A144906 A081789
Adjacent sequences: A194934 A194935 A194936 * A194938 A194939 A194940
nonn
Paul D. Hanna, Sep 05 2011
approved
