T(2n-1,n-2), T given by A026692.

Terms

a(0) =1a(1) =5a(2) =35a(3) =137a(4) =844a(5) =3237a(6) =19289a(7) =74075a(8) =435901a(9) =1681705a(10) =9840202a(11) =38142908a(12) =222555244a(13) =866299556a(14) =5047109045a(15) =19716828587a(16) =114778868635a(17) =449771556357