a(n) = n^2 * binomial(4*n, n).

Terms

a(0) =0a(1) =4a(2) =112a(3) =1980a(4) =29120a(5) =387600a(6) =4845456a(7) =58017960a(8) =673171200a(9) =7625605680a(10) =84766052800a(11) =927990034972