#!/bin/bash

if ! [ $1 ]; then
    for i in 252 235 92 31149 111; do printf "%-8s %d\n" $i: $(bash "$0" $i); done
    exit
fi

c()(echo$1 0
for i in `seq ${#1}`;{
factor ${1::$i}|grep -q :.\\w*$&&for j in `c ${1:$i}`;{ echo $[1+j];};})
(c $1|sort -n;c)|sed 1q