A026408 a(n) = s(k), where, at the end of stage n when forming A026409, k is the greatest integer such that s(j) > 0 for all j < k.

1, 2, 2, 3, 5, 4, 5, 6, 7, 8, 6, 8, 11, 14, 13, 11, 13, 11