CodeForces - 803F

http://codeforces.com/problemset/problem/803/F

#include <iostream>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstring>
#define inf 2147483647
#define N 1000010
#define mod 1000000007
#define p(a) putchar(a)
#define For(i,a,b) for(long long i=a;i<=b;++i)
//by war
//2019.8.21
using namespace std;
long long n,a[N],m=1e5,tot[N],num,cnt,ans;
long long prime[N],mu[N];
bool vis[N];
void in(long long &x){
    long long y=;char c=getchar();x=;
    while(c<''||c>''){if(c=='-')y=-;c=getchar();}
    while(c<=''&&c>=''){ x=(x<<)+(x<<)+c-'';c=getchar();}
    x*=y;
}
void o(long long x){
    if(x<){p('-');x=-x;}
    if(x>)o(x/);
    p(x%+'');
}

void Euler(){
    mu[]=;
    For(i,,1e5){
        if(!vis[i]) prime[++cnt]=i,mu[i]=-;
        for(long long j=;j<=cnt&&i*prime[j]<=1e5;j++){
            vis[i*prime[j]]=;
            if(i%prime[j]==){
                mu[i*prime[j]]=;
                break;
            }
            mu[i*prime[j]]=-mu[i];
        }
    }
}

long long ksm(long long a,long long b){
    long long r=;
    while(b>){
        if(b&)
            r=r*a%mod;
        a=a*a%mod;
        b>>=;
    }
    return r;
}

signed main(){
    in(n);
    Euler();
    For(i,,n)
        in(a[i]),tot[a[i]]++;
    For(i,,m){
        num=;
        for(long long k=;k*i<=m;k++)
            num+=tot[k*i];
        ans+=mu[i]*(ksm(,num)-);
        ans%=mod;
    }
    o((ans+mod)%mod);
    return ;
}