Numbers n such that string 7,4 occurs in the base 10 representation of n but not of n-1.

Terms

a(0) =74a(1) =174a(2) =274a(3) =374a(4) =474a(5) =574a(6) =674a(7) =740a(8) =774a(9) =874a(10) =974a(11) =1074a(12) =1174a(13) =1274a(14) =1374a(15) =1474a(16) =1574a(17) =1674a(18) =1740a(19) =1774a(20) =1874a(21) =1974a(22) =2074a(23) =2174a(24) =2274a(25) =2374a(26) =2474a(27) =2574a(28) =2674a(29) =2740