# 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")
int g,k,t,n,p,a[50000005],b[50000005],spf[50000005],m=5*1e7;
long long res;
int tinh(int x)
{
    g = 1;
    k =0;
    while (x > 1)
    {
        t = spf[x];
        k = 0;
        while (spf[x] == t)
        {
            k++;
            x /= spf[x];
        }
        if (k%2!=0) g *= t;
    }
    return g;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for (int i = 1; i <= m; i++) 
    {
        spf[i] = i;
    }
    for (int i = 2; i*i <= m; i++)
    {
        if (spf[i] == i)
        {
            for (int j = i*i; j <= m; j += i)
            {
                if (spf[j] == j) 
                {
                    spf[j] = i;
                }
            }
        }
    }
    for (int i = 1; i <= n; i++)
    {
        a[i] = tinh(i);
    }
    for (int i = 1; i <= n; i++)
    {
        b[a[i]]++;
    }
    for (int i = 1; i <= n; i++)
    {
        res += (b[i]*b[i]);
    }
    cout << res;

}