A026879 T(2n+1,n+4), T given by A026758.
1, 9, 56, 300, 1488, 7061, 32617, 148166, 666122, 2976438, 13256927, 58977774, 262470955, 1169754507, 5224863646, 23403066235, 105163633173, 474212892828, 2146200885977, 9749771934555, 44458458762351, 203486694636257, 934775275401371
Offset: 3