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=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(long long x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

void Euler(){
    mu[1]=1;
    For(i,2,1e5){
        if(!vis[i]) prime[++cnt]=i,mu[i]=-1;
        for(long long j=1;j<=cnt&&i*prime[j]<=1e5;j++){
            vis[i*prime[j]]=1;
            if(i%prime[j]==0){
                mu[i*prime[j]]=0;
                break;
            }
            mu[i*prime[j]]=-mu[i];
        }
    }
}

long long ksm(long long a,long long b){
    long long r=1;
    while(b>0){
        if(b&1)
            r=r*a%mod;
        a=a*a%mod;
        b>>=1;
    }
    return r;
}

signed main(){
    in(n);
    Euler();
    For(i,1,n)
        in(a[i]),tot[a[i]]++;
    For(i,1,m){
        num=0;
        for(long long k=1;k*i<=m;k++)
            num+=tot[k*i];
        ans+=mu[i]*(ksm(2,num)-1);
        ans%=mod; 
    }
    o((ans+mod)%mod);
    return 0;
}