a(n) = (5*n)^6.

Terms

a(0) =0a(1) =15625a(2) =1000000a(3) =11390625a(4) =64000000a(5) =244140625a(6) =729000000a(7) =1838265625a(8) =4096000000a(9) =8303765625a(10) =15625000000a(11) =27680640625a(12) =46656000000a(13) =75418890625a(14) =117649000000a(15) =177978515625a(16) =262144000000