Numbers n for which there are no solutions to k - A002828(k) = n for any k, in other words, numbers n such that (A002828(1+n) <> 1) and (A002828(2+n) <> 2) and (A002828(3+n) <> 3) and (A002828(4+n) <> 4), as the maximum value that A002828 may obtain is 4.