#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>

using Int = long long;
const Int M = 1000000000 + 7;

int main() {
  int n, k;
  std::cin >> n >> k;
  std::vector<std::vector<Int>> count(n + 1, std::vector<Int>(k + 1, 0));
  count[0][0] = 1;
  for (int ni = 0; ni < n; ++ni) {
    for (int ki = 0; ki <= k; ++ki) {
      for (int nj = 0; nj <= ni; ++nj) {
        int next_inv = ki + nj;
        if (next_inv > k) continue;
        count[ni + 1][next_inv] = (count[ni + 1][next_inv] + count[ni][ki]) % M;
      }
    }
  }
  Int ans = 0;
  for (const auto & c : count[n]) ans = (ans + c) % M;
  std::cout << ans << std::endl;
  return 0;
}