A108993 - OEIS

%I #3 Mar 30 2012 18:36:46

%S 1,1,3,19,205,3276,70852,1953715,65904057,2639266228,122677374326,

%T 6503266277223,387708627582311,25700183133977665,1876381387159576676,

%U 149695388098709302361,12961535832843534300945

%N a(n) = A108992(n)/(n+1). A(x) = 1/x*series_reversion(x/G108996(x)) where G108996(x) is g.f. of A108996.

%C A108992 is the second diagonal of triangle A108990, in which the g.f. of row n, R_n(x), satisfies: [x^k] R_{n+1}(x) = [x^k] (1 + x*R_n(x))^(n+1) for k=0..n+1.

%o (PARI) {a(n)=local(F=1+x*O(x^n));for(m=1,n+1,F=(1+x*F)^m);polcoeff(F,n)/(n+1)}

%Y Cf. A108990, A108991, A108992, A108994, A108995, A108996.

%K nonn

%O 0,3

%A _Paul D. Hanna_, Jun 15 2005