Define the following order among all natural numbers except for 2 and 1: [ 4gg 6gg 3gg dots gg 4ngg 4n+2gg 2n+1gg 4n+4ggdots ] Let $f$ be a continuous interval map. We show that if $mgg s$ and $f$ has a cycle with no division (no block structure) of period $m$ then $f$ has also a cycle with no division (no block structure) of period $s$. We describe possible sets of periods of cycles of $f$ with no division and no block structure.