A044439 Numbers n such that string 2,0 occurs in the base 3 representation of n but not of n+1.

6, 15, 20, 24, 33, 42, 47, 51, 62, 69, 74, 78, 87, 96, 101, 105, 114, 123, 128, 132, 143, 150, 155, 159, 188, 195, 204, 209, 213, 224, 231, 236, 240, 249, 258, 263, 267, 276, 285, 290, 294, 305, 312, 317, 321, 330, 339, 344, 348