#include<fstream>

using namespace std;

int ok,maxi,val,n,i,j,nr,pr[1009],s[1000009];
char ap[1000009],smn[1000009],nu[1000009],cr[1000009];
long long cat,rez;

int main()
{
ifstream f("pairs.in");
ofstream g("pairs.out");
f>>n;
rez=(long long)1LL*n*(n-1)/2;
while(n)
{
    n--;
    f>>val;
    ap[val]=1;
    if(val>maxi) maxi=val;
}
for(i=2;i<=maxi;i++)
{
    ok=cr[i];
    if(ok==0&&i<=maxi/i)
    {
        val=i*i;
        for(j=val;j<=maxi;j+=val)
            nu[j]=1;
        for(j=i*i;j<=maxi;j+=i)
            cr[j]=1;
    }
    if(ok==0)
    {
        for(j=i;j<=maxi;j+=i)
            smn[j]^=1;
    }
    for(j=i;j<=maxi;j+=i)
        s[i]+=ap[j];
}
for(i=2;i<=maxi;i++)
if(!nu[i])
{
    cat=(long long)s[i]*(s[i]-1)/2;
    if(smn[i]==1) rez-=cat;
    else rez+=cat;
}
g<<rez;
return 0;
}