A044747 Numbers n such that string 3,4 occurs in the base 10 representation of n but not of n+1.

34, 134, 234, 334, 349, 434, 534, 634, 734, 834, 934, 1034, 1134, 1234, 1334, 1349, 1434, 1534, 1634, 1734, 1834, 1934, 2034, 2134, 2234, 2334, 2349, 2434, 2534, 2634, 2734, 2834, 2934, 3034, 3134, 3234, 3334, 3349, 3499