OFFSET
0,3
COMMENTS
In table A124540, the g.f. of row n, R_n(y), simultaneously satisfies: R_n(y) = [ Sum_{k>=0} y^k*R_k(y)^n ]^n for n>=0.
EXAMPLE
G.f.: A(x) = R_2(x)/R_1(x), where row g.f.s are:
R_2(x) = 1 + 2x + 7x^2 + 26x^3 + 107x^4 + 486x^5 + 2398x^6 + ... and
R_1(x) = 1 + x + 2x^2 + 5x^3 + 16x^4 + 62x^5 + 274x^6 + ..., so that
A(x) = 1 + x + 4*x^2 + 15*x^3 + 63*x^4 + 295*x^5 + 1502*x^6 + ...
PROG
(PARI) {a(n)=local(R); R=vector(n+3, r, vector(n+3, c, 1)); for(i=0, n+2, for(r=0, n+2, R[r+1]=Vec(sum(c=0, n, x^c*Ser(R[c+1])^(r*c)+O(x^(n+1)))))); Vec(Ser(R[3])^2/Ser(R[2])+O(x^(n+1)))[n+1]}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 05 2006
STATUS
approved