#include <cstdio>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <math.h>
#include <algorithm>
#include <utility>
#include <string>
#include <functional>
#include <sstream>
#include <fstream>
#include <iostream>
using namespace std;
#define FOR(i,a,b) for (i=a;i<=b;i++)
#define fori(it,v) for (it=(v).begin();it!=(v).end();it++)
#define pb push_back
#define mp make_pair
#define fs first
#define ss second
#define all(c) c.begin(),c.end()
#define pf push_front
#define popb pop_back
#define popf pop_front
int c[1000005],a[1000005];
vector<bool> p(1000005);
void ciur_patrate(int n)
{
	double aux=sqrt(n);
	int i,j;
	FOR(i,2,n)
		if (c[i]==0)
		{
			for (j=i;j<=n;j+=i)
				if (c[j]!=-1)
					c[j]++;
			if (i<=aux)
				for (j=i*i;j<=n;j+=i*i)
				{
					c[j]=-1;

				}
		}
}
void ciur2(int n)
{
	int i,j;
	for (i=2;i<=n;i++)
		if (c[i]!=-1)
			for (j=i;j<=n;j+=i)
			{
			//	printf("%d\n",j);
				if (p[j])
					a[i]++;
			}
}
long long rez(int n)
{
	long long val=(long long)n*(long long)(n-1)/2;
	int i;
	//printf("%lld\n",val);
	FOR(i,2,1000000)
		if (a[i]>1)
		{
			if (c[i]%2)
				val-=(long long)a[i]*(long long)(a[i]-1)/(long long)2;
			else
				val+=(long long)a[i]*(long long)(a[i]-1)/(long long)2;
		//	printf("%lld\n",val);
		}
	return val;
}
int main()
{
	FILE *in,*out;
	int i,n,x;
	in=fopen("pairs.in","r");
	out=fopen("pairs.out","w");
	fscanf(in,"%d",&n);
	FOR(i,1,n)
	{
		fscanf(in,"%d",&x);
		p[x]=1;
	}
	ciur_patrate(1000000);
	ciur2(1000000);
	//for (i=1;i<=30;i++)
	//		printf("c[%d]=%d\n",i,c[i]);
	//for (i=1;i<=20;i++)
	//		printf("a[%d]=%d\n",i,a[i]);
	fprintf(out,"%lld",rez(n));
	fclose(in);
	fclose(out);
	return 0;
}