a(n) = T(2*n+1, n+3), T given by A027935.

Terms

a(0) =1a(1) =22a(2) =155a(3) =709a(4) =2587a(5) =8273a(6) =24416a(7) =68595a(8) =187030a(9) =500950a(10) =1327986a(11) =3499982a(12) =9195035a(13) =24115804a(14) =63192397a(15) =165512723a(16) =433410661a(17) =1134800215a(18) =2971089810a(19) =7778591025a(20) =20364830496a(21) =53316076892a(22) =139583609940a(23) =365435000524a(24) =956721681957