a(n) = (8*n + 4)^5.

Terms

a(0) =1024a(1) =248832a(2) =3200000a(3) =17210368a(4) =60466176a(5) =164916224a(6) =380204032a(7) =777600000a(8) =1453933568a(9) =2535525376a(10) =4182119424a(11) =6590815232a(12) =10000000000a(13) =14693280768a(14) =21003416576a(15) =29316250624a(16) =40074642432a(17) =53782400000a(18) =71008211968a(19) =92389579776a(20) =118636749824a(21) =150536645632a(22) =188956800000