A043879 Numbers n such that 1 and 2 occur juxtaposed in the base 3 representation of n but not of n+1.

5, 7, 17, 23, 25, 32, 34, 53, 59, 61, 71, 77, 79, 86, 88, 98, 104, 106, 113, 115, 161, 167, 169, 179, 185, 187, 215, 221, 223, 233, 239, 241, 248, 250, 260, 266, 268, 275, 277, 296, 302, 304, 314, 320, 322, 329, 331, 341, 347, 349