T(n, 2n-9), T given by A027926.

Terms

a(0) =1a(1) =3a(2) =8a(3) =21a(4) =55a(5) =143a(6) =364a(7) =894a(8) =2098a(9) =4685a(10) =9955a(11) =20175a(12) =39130a(13) =72905a(14) =130965a(15) =227612a(16) =383911a(17) =630191a(18) =1009242a(19) =1580345a(20) =2424289a(21) =3649547a(22) =5399802a(23) =7863034a(24) =11282400a(25) =15969161a(26) =22317933a(27) =30824563a(28) =42106956a(29) =56929205