^                # match beginning of string
    (              # begin first stored group
     1             # match a one
      1+?          # then match one or more ones, minimally.
    )              # end storing first group
    \1+            # match the first group, repeated one or more times.
  $                # match end of string.

##</code><code>##

$y=shift;
for($i=2;$i<=$y;){
    next if$y%$i++;
    $y/=--$i;
    push@x,$i
}
print@{$,=x};

##</code><code>##

$y=shift;for($i=2;$i<=$y;){next if$y%$i++;$y/=--$i;push@x,$i}print@{$,=x};