// URL: https://yukicoder.me/problems/no/1514

import std;

version(unittest) {} else
void main()
{
  int N; io.getV(N);

  auto a = new bool[](N+1), b = new int[](N+1);
  a[2..$] = true;
  foreach (i; 1..N+1) b[i] = i;

  foreach (i; 2..isqrt(N)+1) {
    if (!a[i]) continue;
    for (auto j = i*2; j <= N; j += i) a[i] = false;
    auto i2 = i*i;
    for (auto j = i2; j <= N; j += i*i)
      while (b[j] % i2 == 0) b[j] /= i2;
  }

  auto c = new int[](N+1);
  foreach (bi; b[1..N+1]) ++c[bi];

  io.put(c.map!"a*a".sum);
}

pragma(inline)
{
  auto lowerBoundBy(alias conv = "a", alias comp = "a<b", R, T)(const R a, const T v)
  {
    return a.sortedTuple!(conv, comp).lowerBound(tuple(a.front, v)).map!"a[0]";
  }

  auto upperBoundBy(alias conv = "a", alias comp = "a<b", R, T)(const R a, const T v)
  {
    return a.sortedTuple!(conv, comp).upperBound(tuple(a.front, v)).map!"a[0]";
  }

  auto sortedTuple(alias conv = "a", alias comp = "a<b", R)(const R a)
  {
    alias convFun = unaryFun!conv, compFun = binaryFun!comp;
    return a.map!(e => tuple(e, convFun(e))).assumeSorted!((a, b) => compFun(a[1], b[1]));
  }
}

pure nothrow @nogc @safe
{
  T isqrt(T)(T n)
    if (is(T == int) || is(T == long))
  {
    static if (is(T == int)) auto max = 46_341;
    else static if (is(T == long)) auto max = 3_037_000_500L;
    return iota(T(0), max).lowerBoundBy!("a^^2", "a<=b")(n).back;
  }
  T icbrt(T)(T n)
    if (is(T == int) || is(T == long))
  {
    static if (is(T == int)) auto max = 1_291;
    else static if (is(T == long)) auto max = 2_097_152L;
    return iota(T(0), max).lowerBoundBy!("a^^3", "a<=b")(n).back;
  }
}

auto io = IO!()();
struct IO(alias IN = stdin, alias OUT = stdout)
{
  import core.stdc.stdlib : exit;

  void getV(T...)(ref T v)
  {
    foreach (ref w; v) get(w);
  }
  void getA(T)(size_t n, ref T v)
    if (hasAssignableElements!T)
  {
    v = new T(n);
    foreach (ref w; v) get(w);
  }
  void getC(T...)(size_t n, ref T v)
    if (allSatisfy!(hasAssignableElements, T))
  {
    foreach (ref w; v) w = new typeof(w)(n);
    foreach (i; 0..n) foreach (ref w; v) get(w[i]);
  }
  void getM(T)(size_t r, size_t c, ref T v)
    if (hasAssignableElements!T && hasAssignableElements!(ElementType!T))
  {
    v = new T(r);
    foreach (ref w; v) getA(c, w);
  }
  template getS(E...)
  {
    void getS(T)(size_t n, ref T v)
    {
      v = new T(n);
      foreach (ref w; v) foreach (e; E) mixin("get(w."~e~");");
    }
  }

  const struct PutConf
  {
    bool newline = true, flush, exit;
    string floatFormat = "%.10f", delimiter = " ";
  }

  void put(alias conf = "{}", T...)(T v)
  {
    putMain!conf(v);
  }
  void putB(alias conf = "{}", S, T)(bool c, S t, T f)
  {
    if (c) put!conf(t);
    else put!conf(f);
  }
  void putRaw(T...)(T v)
  {
    OUT.write(v);
    OUT.writeln;
  }

  private
  {
    dchar[] buf;
    auto sp = (new dchar[](0)).splitter;

    void nextLine()
    {
      IN.readln(buf);
      sp = buf.splitter;
    }
    void get(T)(ref T v)
    {
      if (sp.empty) nextLine();
      v = sp.front.to!T;
      sp.popFront();
    }

    void putMain(alias conf, T...)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      foreach (i, w; v) {
        putOne!conf(w);
        if (i+1 < v.length) OUT.write(c.delimiter);
      }
      static if (c.newline) OUT.writeln;
      static if (c.flush) OUT.flush();
      static if (c.exit) exit(0);
    }
    void putOne(alias conf, T)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      static if (isInputRange!T && !isSomeString!T) putRange!conf(v);
      else static if (isFloatingPoint!T) OUT.write(format(c.floatFormat, v));
      else static if (hasMember!(T, "fprint")) v.fprint(OUT);
      else OUT.write(v);
    }
    void putRange(alias conf, T)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      auto w = v;
      while (!w.empty) {
        putOne!conf(w.front); w.popFront();
        if (!w.empty) OUT.write(c.delimiter);
      }
    }
  }
}