a(n) = T(2n-1,n-2), T given by A026536.

Terms

a(0) =1a(1) =2a(2) =10a(3) =36a(4) =150a(5) =602a(6) =2485a(7) =10256a(8) =42687a(9) =178300a(10) =747912a(11) =3146936a(12) =13278707a(13) =56163758a(14) =238052050a(15) =1010857520a(16) =4299545769a(17) =18314436414a(18) =78115839734a(19) =333583225740