#include<fstream>
using namespace std;
ifstream cin("pairs.in");
ofstream cout("pairs.out");
int n,x,Maxim;
int NrEl[1000005],PrDesc[1000005],PrUnic[1000005];
bool Prez[1000005];
long long Total,Rez;
int main(){

    cin>>n;

    for(int i=1;i<=n;i++){

        cin>>x;
        Maxim=max(x,Maxim);
        Prez[x]=1;

    }

    for(int i=2;i<=Maxim;i+=2){

        PrDesc[i]++;
        PrUnic[i]=i/2;

    }

    for(int i=3;i<=Maxim;i+=2)
        PrUnic[i]=i;

    for(int i=3;i<=Maxim;i+=2)
        if(PrDesc[i]==0)
            for(int j=i;j<=Maxim;j+=i){

                PrDesc[j]++;
                PrUnic[j]/=i;

            }

    for(int i=2;i<=Maxim;i++)
        if(PrUnic[i]==1)
            for(int j=i;j<=Maxim;j+=i)
                 NrEl[i]+=Prez[j];

    Total=1LL*n*(n-1)/2;

    for(int i=2;i<=Maxim;i++)

        if(PrUnic[i]==1){

            if(PrDesc[i]%2==0)
                Rez-=1LL*NrEl[i]*(NrEl[i]-1)/2;

            else
                Rez+=1LL*NrEl[i]*(NrEl[i]-1)/2;

        }

    cout<<Total-Rez;

}