#!/usr/bin/perl -w
use strict;

my($p,$x)=3;p:{$x=0;x:{$_='s`.*(\\$x\\*\\*2\\+\\$x\\+\\$p).*`$1`ee';
eval"y/\\\\//d;$_";keys%_>$ARGV[0]-2?last p:(1x($_))!~/^(11+?)\1+$/x
&&!exists$_{$_}?++$_{$_}:1;++$x;;$x<$p?goto x:last}$p=(sort{$b<=>$a}
keys%_)[0];;goto p}$,=$";eval "@{[print=>q<2,sort{$a<=>$b}keys%_>]}"