A044752 Numbers n such that string 3,9 occurs in the base 10 representation of n but not of n+1.

39, 139, 239, 339, 399, 439, 539, 639, 739, 839, 939, 1039, 1139, 1239, 1339, 1399, 1439, 1539, 1639, 1739, 1839, 1939, 2039, 2139, 2239, 2339, 2399, 2439, 2539, 2639, 2739, 2839, 2939, 3039, 3139, 3239, 3339, 3399, 3439