a(n) = T(2*n, n+3), T given by A027011.

Terms

a(0) =1a(1) =10a(2) =203a(3) =1719a(4) =9484a(5) =40615a(6) =147760a(7) =481849a(8) =1458335a(9) =4194686a(10) =11658332a(11) =31674918a(12) =84807212a(13) =224985864a(14) =593525255a(15) =1560542957a(16) =4095205128a(17) =10735046293a(18) =28123686540a(19) =73654666767a(20) =192865240859a(21) =504973920796