Numbers n such that string 6,9 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =69a(1) =169a(2) =269a(3) =369a(4) =469a(5) =569a(6) =669a(7) =690a(8) =769a(9) =869a(10) =969a(11) =1069a(12) =1169a(13) =1269a(14) =1369a(15) =1469a(16) =1569a(17) =1669a(18) =1690a(19) =1769a(20) =1869a(21) =1969a(22) =2069a(23) =2169a(24) =2269a(25) =2369a(26) =2469a(27) =2569a(28) =2669a(29) =2690