Numbers n such that string 3,9 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =39a(1) =139a(2) =239a(3) =339a(4) =390a(5) =439a(6) =539a(7) =639a(8) =739a(9) =839a(10) =939a(11) =1039a(12) =1139a(13) =1239a(14) =1339a(15) =1390a(16) =1439a(17) =1539a(18) =1639a(19) =1739a(20) =1839a(21) =1939a(22) =2039a(23) =2139a(24) =2239a(25) =2339a(26) =2390a(27) =2439a(28) =2539a(29) =2639