#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  scanf("%d %d", &n, &m), ++n;
  long long ans = 0;
  for (int a = m + 1; a <= n / 2; ++a) {
    int tmp = 0;
    for (int b = m + 1, c = n - m - 1; b < n - m && c > m; ++b) {
      while (c > m && a * ((a << 1) + b - (n << 1) - c) >= -c * (n + b)) --c;
      tmp += c - m;
    }
    if (a != n - a) tmp *= 2;
    ans += tmp;
  }
  cout << ans * 3 << endl;
}
