using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var dp = new int[n + 1];
        for (var i = 1; i <= n; ++i) dp[i] = i;
        for (var i = 2; i * i <= n; ++i)
        {
            for (var j = i * i; j <= n; j += i * i)
            {
                while(dp[j] % (i * i) == 0) dp[j] /= i * i;
            }
        }
        var ans = 0L;
        var dic = new int[n + 1];
        for (var i = 1; i <= n; ++i)
        {
            ans += dic[dp[i]] * 2 + 1;
            ++dic[dp[i]];
        }
        WriteLine(ans);
    }
}