a(n) = (9*n + 1)^3.

Terms

a(0) =1a(1) =1000a(2) =6859a(3) =21952a(4) =50653a(5) =97336a(6) =166375a(7) =262144a(8) =389017a(9) =551368a(10) =753571a(11) =1000000a(12) =1295029a(13) =1643032a(14) =2048383a(15) =2515456a(16) =3048625a(17) =3652264a(18) =4330747a(19) =5088448a(20) =5929741a(21) =6859000a(22) =7880599a(23) =8998912