a(n) = p^5*(p-1) where p = prime(n).

Terms

a(0) =32a(1) =486a(2) =12500a(3) =100842a(4) =1610510a(5) =4455516a(6) =22717712a(7) =44569782a(8) =141599546a(9) =574312172a(10) =858874530a(11) =2496382452a(12) =4634248040a(13) =6174354606a(14) =10549870322a(15) =21746165636a(16) =41465609342a(17) =50675778060a(18) =89108257062a(19) =126296054570