#include <iostream>
using namespace std;
 
int main() {
	long long i,sum=0;
	long long zeta(long long);
	for(i=2;i<=2500;i++)
		sum+=zeta(i*(2*i-1));
	cout<<sum;
	return 0;
}
long long zeta(long long n)
	{
		bool isprime(long long);
		long long z,ret;
		for(z=n-1;z<n;z--)
			{
				if(isprime(z))
					{
						ret=z;
						break;
					}
			}
		return ret;
	}
bool isprime(long long test)
	{
		bool ch=true;
		long long i;
		for(i=2;i*i<=test;i++)
			{
				if(test%i==0)
					ch=false;
			}
		return ch;
	}

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