a(n) = 4*n*(4*n-1)*(4*n-2)*(4*n-3).

Terms

a(0) =0a(1) =24a(2) =1680a(3) =11880a(4) =43680a(5) =116280a(6) =255024a(7) =491400a(8) =863040a(9) =1413720a(10) =2193360a(11) =3258024a(12) =4669920a(13) =6497400a(14) =8814960a(15) =11703240a(16) =15249024a(17) =19545240a(18) =24690960a(19) =30791400a(20) =37957920a(21) =46308024a(22) =55965360a(23) =67059720a(24) =79727040a(25) =94109400a(26) =110355024a(27) =128618280a(28) =149059680a(29) =171845880