a(n) = A001333(n) - (-2)^(n-1), n > 0.

Terms

a(0) =0a(1) =5a(2) =3a(3) =25a(4) =25a(5) =131a(6) =175a(7) =705a(8) =1137a(9) =3875a(10) =7095a(11) =21649a(12) =43225a(13) =122435a(14) =259423a(15) =698625a(16) =1541985a(17) =4011971a(18) =9107175a(19) =23143825a(20) =53559817a(21) =133933475a(22) =314086735a(23) =776787009a(24) =1838300625a(25) =4512108515a(26) =10745077143a(27) =26237143825a(28) =62749602745