T(2n-1,n-2), T given by A026568.

Terms

a(0) =1a(1) =3a(2) =13a(3) =60a(4) =225a(5) =1148a(6) =4235a(7) =22296a(8) =82425a(9) =440308a(10) =1634435a(11) =8809736a(12) =32819839a(13) =178029138a(14) =665162897a(15) =3625521728a(16) =13577768505