Numbers n such that string 4,9 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =49a(1) =149a(2) =249a(3) =349a(4) =449a(5) =490a(6) =549a(7) =649a(8) =749a(9) =849a(10) =949a(11) =1049a(12) =1149a(13) =1249a(14) =1349a(15) =1449a(16) =1490a(17) =1549a(18) =1649a(19) =1749a(20) =1849a(21) =1949a(22) =2049a(23) =2149a(24) =2249a(25) =2349a(26) =2449a(27) =2490a(28) =2549a(29) =2649