#include <bits/stdc++.h>
using namespace std;
char buf[1 << 21], *p1 = buf, *p2 = buf;
template <class T>
void read(T &x) {
  x = 0;
  int c = getchar();
  int flag = 0;
  while (c < '0' || c > '9') flag |= (c == '-'), c = getchar();
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
  if (flag) x = -x;
}
template <class T>
T _max(T a, T b) {
  return b < a ? a : b;
}
template <class T>
T _min(T a, T b) {
  return a < b ? a : b;
}
template <class T>
bool checkmax(T &a, T b) {
  return a < b ? a = b, 1 : 0;
}
template <class T>
bool checkmin(T &a, T b) {
  return b < a ? a = b, 1 : 0;
}
int n, m;
void init() {
  read(n);
  read(m);
  ++n;
}
void solve() {
  long long ans = 0;
  int up = n - m - 1;
  for (register int k = m + 1; k <= up; ++k) {
    int i = m + 1, c = 2 * k * k - 2 * n * k;
    for (register int j = up; j >= m + 1; --j) {
      while (i <= up && c + (i - j) * k + (n + n - j) * (n - i) >= 0) ++i;
      if (i <= up)
        ans += up - i + 1;
      else
        break;
    }
  }
  ans *= 3;
  printf("%lld\n", ans);
}
int main() {
  init();
  solve();
  return 0;
}
