Numbers n such that string 5,7 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =57a(1) =157a(2) =257a(3) =357a(4) =457a(5) =557a(6) =570a(7) =657a(8) =757a(9) =857a(10) =957a(11) =1057a(12) =1157a(13) =1257a(14) =1357a(15) =1457a(16) =1557a(17) =1570a(18) =1657a(19) =1757a(20) =1857a(21) =1957a(22) =2057a(23) =2157a(24) =2257a(25) =2357a(26) =2457a(27) =2557a(28) =2570a(29) =2657