A039385 Numbers n such that representation in base 9 has same nonzero number of 4's and 7's.

43, 67, 124, 148, 205, 229, 286, 310, 331, 340, 349, 358, 376, 385, 387, 388, 389, 390, 392, 393, 395, 403, 448, 472, 529, 553, 571, 580, 589, 598, 603, 604, 605, 606, 608, 609, 611, 616, 625, 643, 691, 715, 772, 796, 853, 877, 934, 958, 1015, 1039