A014872 Numbers k that divide s(k), where s(1)=1, s(j)=21*s(j-1)+j.

1, 3, 5, 7, 15, 21, 25, 35, 75, 105, 125, 175, 301, 375, 525, 625, 875, 903, 1389, 1505, 1875, 2625, 3125, 3165, 4375, 4417, 4515, 6945, 7525, 9375, 9723, 11325, 12943, 13125, 13251, 15625, 15825, 21875, 22085, 22155, 22575, 23233, 31375