A047117 T(n,n+2), array T as in A047110.
1, 3, 9, 33, 115, 401, 1482, 5449, 20048, 75303, 283599, 1069860, 4070772, 15539326, 59433763, 228278533, 879053987, 3391075968, 13113667186, 50808921375, 197150760045, 766241841810, 2982295208876, 11621280655944
Offset: 0