#include <bits/stdc++.h>
int n, m;
long long ans;
int main() {
  int i, j, k;
  scanf("%d%d", &n, &m);
  for (i = m + 1; (i << 1) <= n; ++i) {
    k = n - m;
    for (j = m + 1; j <= n - m; ++j) {
      while (k > m && 0 <= (i << 1) * ((i << 1) - j - ((n << 1) - k + 2)) +
                               3 * j * k + j * ((n << 1) - k + 2))
        --k;
      ans += k - m;
    }
  }
  ans <<= 1;
  if (n & 1) {
    i = (n >> 1) + 1;
    k = n - m;
    for (j = m + 1; j <= n - m; ++j) {
      while (k > m && 0 <= (i << 1) * ((i << 1) - j - ((n << 1) - k + 2)) +
                               3 * j * k + j * ((n << 1) - k + 2))
        --k;
      ans += k - m;
    }
  }
  printf("%I64d\n", ans * 3);
  return 0;
}
