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

Terms

a(0) =27a(1) =127a(2) =227a(3) =279a(4) =327a(5) =427a(6) =527a(7) =627a(8) =727a(9) =827a(10) =927a(11) =1027a(12) =1127a(13) =1227a(14) =1279a(15) =1327a(16) =1427a(17) =1527a(18) =1627a(19) =1727a(20) =1827a(21) =1927a(22) =2027a(23) =2127a(24) =2227a(25) =2279a(26) =2327a(27) =2427a(28) =2527a(29) =2627