A212421 - OEIS

%I #7 May 16 2012 08:50:49

%S 1,1,3,6,17,42,118,320,861,2442,6658,18686,52100,146832,410990,

%T 1161722,3282403,9283968,26336598,74712158,212613094,605118528,

%U 1726261816,4926677982,14079210098,40247549662,115175011608,329707161766,944566633454,2707713181042

%N Central coefficients of triangle A096815.

%F a(n) = T(2n,n), where T(n,k) = A096815(n,k).

%t T[n_,k_] := T[n,k] = If[n < k || k < 0, 0, If[k = 1 || k == n, 1, Sum[T[n-k,j]T[k,k-j],{j,0,k}]]]

%t Table[T[2n, n], {n, 0, 50}]

%Y Cf. A096815, A096816, A212264, A212265, A212422

%K nonn

%O 0,3

%A _Emanuele Munarini_, May 16 2012