a(n) = 4^n*(2n + 1)^2.

Terms

a(0) =1a(1) =36a(2) =400a(3) =3136a(4) =20736a(5) =123904a(6) =692224a(7) =3686400a(8) =18939904a(9) =94633984a(10) =462422016a(11) =2218786816a(12) =10485760000a(13) =48922361856a(14) =225754218496