%I #9 Jan 25 2015 16:07:08

%S 2,1,1,1,6,27,122,555,2530,11564,52994,243467,1121292,5176432,

%T 23952042,111076279,516217844,2404051080,11218106730,52447788512,

%U 245659502752,1152673780946,5417690242696,25505048506311,120257626246616,567864679387562

%N a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5.

%F Conjecture: n*a(n) +4*(-2*n+3)*a(n-1) +12*(n-3)*a(n-2) +6*(2*n-9)*a(n-3) +16*(n-6)*a(n-4)=0. - _R. J. Mathar_, Nov 21 2014

%F G.f.: 1/2 - sqrt(16*x^4+12*x^3+12*x^2-8*x+1)/2. - _Vaclav Kotesovec_, Jan 25 2015

%t nmax = 30; aa = ConstantArray[0,nmax]; aa[[1]] = 2; aa[[2]] = 1; aa[[3]] = 1; aa[[4]] = 1; Do[aa[[n]] = Sum[aa[[k]]*aa[[n-k]],{k,1,n-1}],{n,5,nmax}]; aa (* _Vaclav Kotesovec_, Jan 25 2015 *)

%K nonn

%O 1,1

%A _Clark Kimberling_