#include <bits/stdc++.h>
using namespace std;

#pragma GCC target("avx")
#pragma GCC optimize("O2")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")

#define ll long long
#define endl "\n"
#define pb push_back
#define ff first
#define ss second
#define ii pair<int, int>
#define vi vector<int>
#define vii vector<pair<int, int>>
#define vvi vector<vi>
#define mii map<int, int>
#define rep(i, a, b) for (int i = a; i <= b; i++)
#define _READ(name) freopen(name, "r", stdin)
#define _WRITE(name) freopen(name, "w", stdout)

int n; const int mx = 5e7 + 3;
int sq[mx];
int mp[mx];
int spf[mx];

void Prepare() {
    cin >> n;
}

void ppc() {
	for (int i = 1; i < mx; i++) spf[i] = i;
	for (int i = 2; i * i < mx; i++) {
		if (spf[i] == i) {
			for (int j = i*i; j < mx; j += i) {
				if (spf[j] == j) spf[j] = i;
			}
		}
	}
}

int tinh(int x) {
	int y = 1;
	while (x > 1) {
		int cur = spf[x], c = 0;
		while (cur == spf[x]) {
			x /= cur;
			c++;
		}
		if (c%2==1) y *= cur;
	}
	
	return y;
}

void COOOOK() {
	ppc();
	for (int i = 1; i <= n; i++) sq[i] = tinh(i);
	
	ll ans = 0;
	rep(i, 1, n) {
		mp[sq[i]]++;
	}
	
	rep(i, 1, n) {
		ans += (mp[i]*1ll*mp[i]);
	}
	cout << ans;
}

void Eat() {

}

void Wash() {

}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    int TEST = 1;
    while (TEST--) {
        Prepare();
        COOOOK();
        Eat();
        Wash();
    }

    return 0;

}