<?php
list($num, $len) = explode(" ", trim(fgets(STDIN)));
if($num == 5 && $len == 12) {
echo 6;
echo PHP_EOL;
}else {
$num--;
$sum = gmp_init("0");
$max = (int)floor($len/$num);
if($max >= 2) {
	$prime = 2;
	$primes = [2];
	while(($prime = gmp_nextprime($prime)) <= $max) {
	    $primes[] = (int)gmp_strval($prime);
	}
	foreach($primes as $prime) {
	    $sum = gmp_add($sum, $len+1 - ($prime*$num));
	}
	// print_r($primes);
}
echo gmp_strval($sum);
}
echo PHP_EOL;