a(n) = (7*n + 1)^3.

Terms

a(0) =1a(1) =512a(2) =3375a(3) =10648a(4) =24389a(5) =46656a(6) =79507a(7) =125000a(8) =185193a(9) =262144a(10) =357911a(11) =474552a(12) =614125a(13) =778688a(14) =970299a(15) =1191016a(16) =1442897a(17) =1728000a(18) =2048383a(19) =2406104a(20) =2803221a(21) =3241792a(22) =3723875a(23) =4251528a(24) =4826809