Numbers n such that string 7,2 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =72a(1) =172a(2) =272a(3) =372a(4) =472a(5) =572a(6) =672a(7) =720a(8) =772a(9) =872a(10) =972a(11) =1072a(12) =1172a(13) =1272a(14) =1372a(15) =1472a(16) =1572a(17) =1672a(18) =1720a(19) =1772a(20) =1872a(21) =1972a(22) =2072a(23) =2172a(24) =2272a(25) =2372a(26) =2472a(27) =2572a(28) =2672a(29) =2720