Numbers n such that string 7,8 occurs in the base 10 representation of n but not of n+1.

Terms

a(0) =78a(1) =178a(2) =278a(3) =378a(4) =478a(5) =578a(6) =678a(7) =778a(8) =789a(9) =878a(10) =978a(11) =1078a(12) =1178a(13) =1278a(14) =1378a(15) =1478a(16) =1578a(17) =1678a(18) =1778a(19) =1789a(20) =1878a(21) =1978a(22) =2078a(23) =2178a(24) =2278a(25) =2378a(26) =2478a(27) =2578a(28) =2678a(29) =2778