Binomial coefficient C(4n,n-4).

Terms

a(0) =1a(1) =20a(2) =276a(3) =3276a(4) =35960a(5) =376992a(6) =3838380a(7) =38320568a(8) =377348994a(9) =3679075400a(10) =35607051480a(11) =342700125300