#include #include #include using namespace std; #include struct FFT { using Complex = complex; const double PI = acos(-1); const int sz = 1 << 19; // 524288 void dft(vector &x, bool inv) { for (int i = sz >> 1; i >= 1; i >>= 1) { Complex bs = polar(1.0, 2.0 * PI * i / sz * (inv ? -1 : 1)), w = 1; vector y(sz); for (int j = 0; 2 * j < sz; j += i) { for (int k = 0; k < i; k++) { y[j + k] = x[2 * j + k] + w * x[2 * j + i + k]; y[j + k + (sz >> 1)] = x[2 * j + k] - w * x[2 * j + i + k]; } w *= bs; } x = y; } if (inv) for (int i = 0; i < sz; i++) x[i] /= sz; } vector multiply(vector &a, vector &b) { vector x(sz), y(sz); for (int i = 0; i < (int)a.size(); i++) x[i] = Complex(a[i], 0.0); for (int i = 0; i < (int)b.size(); i++) y[i] = Complex(b[i], 0.0); dft(x, false), dft(y, false); for (int i = 0; i < sz; i++) x[i] *= y[i]; dft(x, true); vector c(sz); for (int i = 0; i < sz; i++) c[i] = (long long)(x[i].real() + 0.5); return c; } } fft; bool is_prime(long long x) { if (x <= 1) return false; for (long long i = 2; i * i <= x; i++) if (x % i == 0) return false; return true; } int main() { int n; cin >> n; vector v(n + 1), w(n * 2 + 1); for (int i = 0; i <= n; i++) v[i] = w[i * 2] = is_prime(i); auto x = fft.multiply(v, v); auto y = fft.multiply(v, x); auto z = fft.multiply(v, w); long long ans = 0; for (int i = 0; i <= n * 3; i++) if (is_prime(i)) ans += y[i] - z[i] * 3; cout << ans / 6 << endl; return 0; }