#include <cstdio>
#include <algorithm>
using namespace std;
long long n,m,x,s,i,j,v[1000005],p[1000005],q[1000005],a[1000005];
int main()
{
    FILE *f=fopen("pairs.in","r");
    FILE *g=fopen("pairs.out","w");
    m=-1;
    fscanf(f,"%lld",&n);
    for(i=1; i<=n; i++)
    {
        fscanf(f,"%lld",&x);
        a[x]=1;
        if(m<x) m=x;
    }
    for(i=1; i<=m; i++)
        for(j=i; j<=m; j+=i)
            p[i]+=(a[j]==1);
    for(i=2; i<=m; i++)
    if(!v[i])
    {
            for(j=i; j<=m; j+=i)
                v[j]++;
            for(j=i*i; j<=m; j+=i*i)
                q[j]=1;
    }
    for(i=1; i<=m; ++i)
    {
        if(q[i]) continue;
        else
        {
            if(v[i]%2) s-=p[i]*(p[i]-1);
            else s+=p[i]*(p[i]-1);
        }
    }
    fprintf(g,"%lld\n",s/2);
    fclose(f); fclose(g);
    return 0;
}