A136997 Numbers n such that n and the square of n use only the digits 1, 2, 4, 7 and 8.

1, 2, 11, 12, 21, 22, 28, 88, 122, 221, 278, 418, 421, 471, 472, 478, 1478, 1488, 2778, 2878, 4141, 4271, 4721, 8472, 8878, 11141, 14771, 21171, 21778, 27771, 27878, 84722, 88418, 88471, 112778, 112878, 118818, 211488, 272841, 277818, 287771, 414418, 422222, 477778, 878221, 884428, 1128222, 1214171, 1477221, 1477421, 2174278, 2178818, 2184441