a(n) = (2*n^2*(n^2 - 3) - (2*n^2 + 1)*(-1)^n + 1)/64.

Terms

a(0) =0a(1) =0a(2) =2a(3) =6a(4) =18a(5) =36a(6) =72a(7) =120a(8) =200a(9) =300a(10) =450a(11) =630a(12) =882a(13) =1176a(14) =1568a(15) =2016a(16) =2592a(17) =3240a(18) =4050a(19) =4950a(20) =6050a(21) =7260a(22) =8712a(23) =10296a(24) =12168a(25) =14196a(26) =16562a(27) =19110a(28) =22050a(29) =25200