Emeric (and Seqfans),
Correction to my typo in prior e-mail:
> I will not attempt to give a simpler g.f. for your M[n], where:
> M[n+1](z) = M[n](z)*C[n](z^n*M[n-1]^(n-1));
that should have been:
M[1](z) = 1/(1-z);
M[n+1](z) = M[n](z)*C[n+1](z^(n+1)*M[n]^n);
This was more clearly given by Emeric, but I correct myself for the sake
of accuracy.
Paul