T(2n+1,n+4), T given by A026758.

Terms

a(0) =1a(1) =9a(2) =56a(3) =300a(4) =1488a(5) =7061a(6) =32617a(7) =148166a(8) =666122a(9) =2976438a(10) =13256927a(11) =58977774a(12) =262470955a(13) =1169754507a(14) =5224863646a(15) =23403066235a(16) =105163633173a(17) =474212892828