Numbers n such that string 6,7 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =67a(1) =167a(2) =267a(3) =367a(4) =467a(5) =567a(6) =667a(7) =670a(8) =767a(9) =867a(10) =967a(11) =1067a(12) =1167a(13) =1267a(14) =1367a(15) =1467a(16) =1567a(17) =1667a(18) =1670a(19) =1767a(20) =1867a(21) =1967a(22) =2067a(23) =2167a(24) =2267a(25) =2367a(26) =2467a(27) =2567a(28) =2667a(29) =2670