A048391 Replacing digits d in decimal expansion of n with d^3 yields a square.

0, 1, 4, 9, 21, 100, 400, 561, 900, 2100, 8821, 10000, 11221, 17821, 40000, 56100, 73221, 90000, 210000, 211201, 518041, 882100, 1000000, 1001614, 1002621, 1012021, 1012224, 1122100, 1302801, 1782100, 4000000, 5012214, 5610000