A135870 G.f. A(x) = (1 + x*A(3x))^2.

1, 2, 13, 246, 13554, 2210436, 1076561037, 1570714992558, 6871883750090694, 90179738434097457084, 3550105797469080332658354, 419263945026939228053105930844, 148543119421079567735277052592081220

Offset: 0

Author

Paul D. Hanna, Dec 02 2007

Keywords

• nonn

Comments

Self-convolution of A135869.

Crossrefs

Cf. A135868, A135869.

Programs

PARI

{a(n)=local(A=1+x+x*O(x^n));for(i=0,n,A=1+x*subst(A,x,3*x)^2);polcoeff(A^2,n)}