a(n) = 3*binomial(n,4) - 6*binomial(n,3) + 4*binomial(n,2) - 2.

Terms

a(0) =-2a(1) =-2a(2) =2a(3) =4a(4) =1a(5) =-7a(6) =-17a(7) =-23a(8) =-16a(9) =16a(10) =88a(11) =218a(12) =427a(13) =739a(14) =1181a(15) =1783a(16) =2578a(17) =3602a(18) =4894a(19) =6496a(20) =8453a(21) =10813a(22) =13627a(23) =16949a(24) =20836a(25) =25348a(26) =30548a(27) =36502a(28) =43279a(29) =50951