Numbers whose base-7 representation contains exactly three 4's.

Terms

a(0) =228a(1) =571a(2) =914a(3) =1257a(4) =1404a(5) =1453a(6) =1502a(7) =1551a(8) =1572a(9) =1579a(10) =1586a(11) =1593a(12) =1596a(13) =1597a(14) =1598a(15) =1599a(16) =1601a(17) =1602a(18) =1607a(19) =1614a(20) =1649a(21) =1698a(22) =1943a(23) =2286a(24) =2629a(25) =2972a(26) =3315a(27) =3658a(28) =3805a(29) =3854