A044585 Numbers n such that string 2,1 occurs in the base 8 representation of n but not of n+1.

17, 81, 143, 145, 209, 273, 337, 401, 465, 529, 593, 655, 657, 721, 785, 849, 913, 977, 1041, 1151, 1167, 1169, 1233, 1297, 1361, 1425, 1489, 1553, 1617, 1679, 1681, 1745, 1809, 1873, 1937, 2001, 2065, 2129, 2191, 2193, 2257