Numbers k such that 4 and 9 occur juxtaposed in the base-10 representation of k but not of k-1.

Terms

a(0) =49a(1) =94a(2) =149a(3) =194a(4) =249a(5) =294a(6) =349a(7) =394a(8) =449a(9) =490a(10) =549a(11) =594a(12) =649a(13) =694a(14) =749a(15) =794a(16) =849a(17) =894a(18) =940a(19) =994a(20) =1049a(21) =1094a(22) =1149a(23) =1194a(24) =1249a(25) =1294a(26) =1349a(27) =1394a(28) =1449a(29) =1490