A044372 Numbers n such that string 4,0 occurs in the base 10 representation of n but not of n-1.

40, 140, 240, 340, 400, 440, 540, 640, 740, 840, 940, 1040, 1140, 1240, 1340, 1400, 1440, 1540, 1640, 1740, 1840, 1940, 2040, 2140, 2240, 2340, 2400, 2440, 2540, 2640, 2740, 2840, 2940, 3040, 3140, 3240, 3340, 3400, 3440