A028821 Numbers n such that n^2 has digits in descending order.

0, 1, 2, 3, 8, 9, 10, 20, 21, 29, 30, 31, 80, 88, 90, 100, 200, 210, 290, 300, 310, 800, 880, 900, 1000, 2000, 2100, 2900, 2979, 3000, 3100, 3139, 8000, 8800, 9000, 10000, 20000, 21000, 29000, 29790, 30000, 31000, 31390, 31621, 80000, 88000