A047124 T(n,n-2), array T as in A047120.
1, 1, 6, 22, 86, 335, 1307, 5071, 19664, 76299, 296396, 1152682, 4487818, 17492162, 68252789, 266589233, 1042279572, 4078677195, 15974343417, 62614027433, 245608306154, 964087953123, 3786809126547, 14883181075527
Offset: 2