A055221 T(2n+5,n), array T as in A055216.
1, 7, 36, 157, 625, 2343, 8427, 29406, 100296, 336066, 1110300, 3626559, 11734557, 37673295, 120150909, 381040101, 1202559732, 3779328996, 11833845967, 36934571140, 114947180946, 356828242618, 1105180433704
Offset: 0