%I A112319
%S A112319 1,1,2,9,64,630,7916,121023,2179556,45179508,1059312264,27715541568,
%T A112319 800423573676,25289923553700,867723362137464,32128443862364255,
%U A112319 1276818947065793736,54208515369076658640,2448636361058495090816
%N A112319 Coefficients of x^n in the (n-1)-th self-composition of (x + x^2) for 
               n>=1.
%F A112319 a(n) = [x^n] F_{n-1}(x) where F_n(x) = F_{n-1}(x+x^2) with F_1(x) = x+x^2 
               and F_0(x)=x for n>=1.
%e A112319 Initial terms in self-compositions of (x+x^2) are:
%e A112319 F(x) = x + (1)*x^2
%e A112319 F(F(x)) = x + 2*x^2 + (2)*x^3 + x^4
%e A112319 F(F(F(x))) = x + 3*x^2 + 6*x^3+ (9)*x^4 +...
%e A112319 F(F(F(F(x)))) = x + 4*x^2 + 12*x^3 + 30*x^4 + (64)*x^5 +...
%e A112319 F(F(F(F(F(x))))) = x + 5*x^2 + 20*x^3 + 70*x^4 + 220*x^5 + (630)*x^6 
               +...
%p A112319 {a(n)=local(F=x+x^2, G=x+x*O(x^n));if(n<1,0, for(i=1,n,G=subst(F,x,G));
               return(polcoeff(G,n,x)))}
%Y A112319 Cf. A112317, A112320.
%Y A112319 Sequence in context: A000169 A055860 A152917 this_sequence A038038 A048801 
               A152915
%Y A112319 Adjacent sequences: A112316 A112317 A112318 this_sequence A112320 A112321 
               A112322
%K A112319 nonn
%O A112319 1,3
%A A112319 Paul D. Hanna (pauldhanna(AT)juno.com), Sep 06 2005