a(n) = (8*n + 7)^5.

Terms

a(0) =16807a(1) =759375a(2) =6436343a(3) =28629151a(4) =90224199a(5) =229345007a(6) =503284375a(7) =992436543a(8) =1804229351a(9) =3077056399a(10) =4984209207a(11) =7737809375a(12) =11592740743a(13) =16850581551a(14) =23863536599a(15) =33038369407a(16) =44840334375