A039324 Numbers n such that representation in base 7 has same nonzero number of 3's and 5's.

26, 38, 75, 87, 124, 136, 152, 159, 166, 180, 182, 183, 184, 186, 188, 194, 222, 234, 248, 255, 262, 266, 267, 268, 270, 272, 276, 290, 320, 332, 369, 381, 418, 430, 467, 479, 495, 502, 509, 523, 525, 526, 527, 529, 531, 537, 565, 577, 591, 598, 605, 609