T(2n+1,n+3), T given by A026747.

Terms

a(0) =1a(1) =8a(2) =46a(3) =234a(4) =1124a(5) =5241a(6) =24050a(7) =109429a(8) =495884a(9) =2244060a(10) =10158768a(11) =46055322a(12) =209247370a(13) =953184750a(14) =4354605139a(15) =19954396521a(16) =91721631238a(17) =422908476612