Numbers k such that string 3,4 occurs in the base 7 representation of k but not of k-1.

Terms

a(0) =25a(1) =74a(2) =123a(3) =172a(4) =175a(5) =221a(6) =270a(7) =319a(8) =368a(9) =417a(10) =466a(11) =515a(12) =518a(13) =564a(14) =613a(15) =662a(16) =711a(17) =760a(18) =809a(19) =858a(20) =861a(21) =907a(22) =956a(23) =1005a(24) =1054a(25) =1103a(26) =1152a(27) =1201a(28) =1204a(29) =1225