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

Terms

a(0) =51a(1) =151a(2) =251a(3) =351a(4) =451a(5) =510a(6) =551a(7) =651a(8) =751a(9) =851a(10) =951a(11) =1051a(12) =1151a(13) =1251a(14) =1351a(15) =1451a(16) =1510a(17) =1551a(18) =1651a(19) =1751a(20) =1851a(21) =1951a(22) =2051a(23) =2151a(24) =2251a(25) =2351a(26) =2451a(27) =2510a(28) =2551a(29) =2651