T(2n-1,n-1), T given by A026714.

Terms

a(0) =1a(1) =5a(2) =25a(3) =128a(4) =664a(5) =3468a(6) =18179a(7) =95486a(8) =502130a(9) =2642373a(10) =13910933a(11) =73254357a(12) =385819274a(13) =2032271705a(14) =10705592360a(15) =56397552658a(16) =297114357284