#include<stdio.h>
#include <iostream>
#include <cstring>
#include <math.h>
using namespace std;

int sosu(int);

int main(){
	//while(1){

		long long n,a;
		
		cin>>n>>a;
		int x=a/(n-1);
		long ds=0;
		int z=0;

		for(int d=2;d<=x;d++){
			if(sosu(d)){
				ds+=d;
				z++;
				//printf("%d       %d       %d\n",ds,d,z);
				//cout<<ds<<"      "<<d<<"        "<<z<<endl;
			}
		}
		//printf("%d\n",(a+1)*z-(n-1)*ds);
		cout<<(a+1)*z-(n-1)*ds<<endl;

		
	//}



	
	return 0;
}

int sosu(int n){
	int i;
	for(i=2;i*i<=n;i++) if(n%i==0) return 0;
	return 1;
}