#include <bits/stdc++.h>

#define out(x) cout << #x << '=' << (x) << endl
#define out2(x, y) cout << #x << '=' << (x) << ',' << #y << '=' << (y) << endl 
#define no do { cout << "No" << endl; return; } while(0)
#define yes do { cout << "Yes" << endl; return; } while (0)
#define lowbit(x) ((x) & -(x))

using namespace std;

using ll = long long;

const ll inf = 0x3f3f3f3f3f3f3f3fLL;
const int infi = 0x3f3f3f3f;

template<typename T> ostream & operator << (ostream &out,const set<T>&obj){out<<"set(";for(auto it=obj.begin();it!=obj.end();it++) out<<(it==obj.begin()?"":", ")<<*it;out<<")";return out;}
template<typename T1,typename T2> ostream & operator << (ostream &out,const map<T1,T2>&obj){out<<"map(";for(auto it=obj.begin();it!=obj.end();it++) out<<(it==obj.begin()?"":", ")<<it->first<<": "<<it->second;out<<")";return out;}
template<typename T1,typename T2> ostream & operator << (ostream &out,const pair<T1,T2>&obj){out<<"<"<<obj.first<<", "<<obj.second<<">";return out;}
template<typename T> ostream & operator << (ostream &out,const vector<T>&obj){out<<"vector(";for(auto it=obj.begin();it!=obj.end();it++) out<<(it==obj.begin()?"":", ")<<*it;out<<")";return out;}


void solve() {
    int n;
    cin >> n;
    const int h = n * 2;
    vector<int> minfac(h + 1), primes;
    for (int i = 2; i <= h; i++) {
        if (!minfac[i]) {
            minfac[i] = i;
            primes.push_back(i);
        }
        for (int p : primes) {
            int t = i * p;
            if (t > h) break;
            minfac[t] = p;
            if (p == minfac[i]) break;
        }
    }
    vector<int> ans(n + 1, infi);
    auto calc_fact = [&](int i) -> void {
        unordered_map<int, int> cnt;
        int left = i, right = i + 1;
        while (left > 1) cnt[minfac[left]]++, left /= minfac[left];
        while (right > 1) cnt[minfac[right]]++, right /= minfac[right];
        cnt[2]--;
        
        vector<int> fact = {1};
        for (auto [k, v] : cnt) {
            int now = 0;
            for (int i = 1; i <= v; i++) {
                int high = fact.size();
                for (int j = now; j < high; j++) {
                    if (1LL * fact[j] * k <= n) fact.push_back(fact[j] * k);
                }
                now = high;
            }
        }
        for (int d : fact) ans[d] = min(ans[d], i);
    };
    for (int i = 1; i < n * 2; i++) calc_fact(i);
    
    ll res = 0;
    for (int i = 1; i <= n; i++) res += ans[i];
    
    cout << res << endl;
}

int main(void) {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    int t = 1;
    //cin >> t;
    
    while (t--) {
        solve(); 
    }
}