A124542 Row 2 of rectangular table A124540; equals the self-convolution of A124532 (row 2 of table A124530).

1, 2, 7, 26, 107, 486, 2398, 12668, 70863, 416304, 2552490, 16254406, 107095090, 727834866, 5089682472, 36548625188, 269065010063, 2027942075946, 15630423416331, 123079853443384, 989356860469923, 8112792202324232

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.

Crossrefs

Cf. A124532; A124540 (table); other rows: A124531, 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+O(x^(n+1)))[n+1]}