a(n) = 3*(25*n + 1).

Terms

a(0) =3a(1) =78a(2) =153a(3) =228a(4) =303a(5) =378a(6) =453a(7) =528a(8) =603a(9) =678a(10) =753a(11) =828a(12) =903a(13) =978a(14) =1053a(15) =1128a(16) =1203a(17) =1278a(18) =1353a(19) =1428a(20) =1503a(21) =1578a(22) =1653a(23) =1728a(24) =1803a(25) =1878a(26) =1953a(27) =2028a(28) =2103a(29) =2178