%I #2 Mar 30 2012 18:37:07

%S 1,2,13,246,13554,2210436,1076561037,1570714992558,6871883750090694,

%T 90179738434097457084,3550105797469080332658354,

%U 419263945026939228053105930844,148543119421079567735277052592081220

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

%C Self-convolution of A135869.

%o (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)}

%Y Cf. A135868, A135869.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Dec 02 2007