a(n) = (7*n + 6)^5.

Terms

a(0) =7776a(1) =371293a(2) =3200000a(3) =14348907a(4) =45435424a(5) =115856201a(6) =254803968a(7) =503284375a(8) =916132832a(9) =1564031349a(10) =2535525376a(11) =3939040643a(12) =5904900000a(13) =8587340257a(14) =12166529024a(15) =16850581551a(16) =22877577568a(17) =30517578125