a(n) = T(2n+1, n+4), T given by A027935.

Terms

a(0) =1a(1) =37a(2) =376a(3) =2267a(4) =10220a(5) =38403a(6) =127921a(7) =392688a(8) =1140260a(9) =3189022a(10) =8699540a(11) =23352118a(12) =62048869a(13) =163843187a(14) =431026972a(15) =1131463777a(16) =2966502032a(17) =7772382641a(18) =20356549685a(19) =53305176134a(20) =139569431544a(21) =365416760764a(22) =956698453752