a(n) = if n mod 2 = 1 then n^3*(n-1)^2/2 else n^5/2.

Terms

a(0) =0a(1) =0a(2) =16a(3) =54a(4) =512a(5) =1000a(6) =3888a(7) =6174a(8) =16384a(9) =23328a(10) =50000a(11) =66550a(12) =124416a(13) =158184a(14) =268912a(15) =330750a(16) =524288a(17) =628864a(18) =944784a(19) =1111158a(20) =1600000a(21) =1852200a(22) =2576816a(23) =2944414a(24) =3981312a(25) =4500000a(26) =5940688a(27) =6652854a(28) =8605184a(29) =9560488