A124541 G.f.: A(x) = R_2(x)/R_1(x), where R_2(x) and R_1(x) are the g.f.s of row 2 (A124542) and row 1 (A124531), respectively, of table A124540.

1, 1, 4, 15, 63, 295, 1502, 8167, 46873, 281672, 1761798, 11418480, 76415644, 526594846, 3728435747, 27073765165, 201325681384, 1531247489953, 11899881220174, 94409837555587, 764105555574024, 6304959856949278

Offset: 0

Author

Paul D. Hanna, Nov 05 2006

Keywords

• nonn

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.

Examples

			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 + ...
		

Crossrefs

Cf. A124540 (table); rows: A124531, A124542, A124543, A124544, A124545, A124546.

Programs

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]}