Numbers whose base-7 representation contains exactly three 3's.

Terms

a(0) =171a(1) =514a(2) =857a(3) =1053a(4) =1102a(5) =1151a(6) =1179a(7) =1186a(8) =1193a(9) =1197a(10) =1198a(11) =1199a(12) =1201a(13) =1202a(14) =1203a(15) =1207a(16) =1214a(17) =1221a(18) =1249a(19) =1298a(20) =1347a(21) =1543a(22) =1886a(23) =2229a(24) =2572a(25) =2915a(26) =3258a(27) =3454a(28) =3503a(29) =3552