a(n) = T(2n+1, n+3), T given by A027948.

Terms

a(0) =1a(1) =7a(2) =92a(3) =591a(4) =2683a(5) =9955a(6) =32551a(7) =98086a(8) =280271a(9) =773906a(10) =2091266a(11) =5576298a(12) =14750858a(13) =38839257a(14) =101995694a(15) =267462041a(16) =700813797a(17) =1835540197a(18) =4806538617a(19) =12585017712a(20) =32949712457a(21) =86265626164a(22) =225849041524a(23) =591283811748