#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const ll MOD = 1000000007;

ll dp[50000];

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N, K;
    cin >> N >> K;
    dp[0] = 1;
    for (int i = 2; i <= N; i++) {
        for (int j = (i - 1) * (i - 2) / 2; j >= 0; j--) {
            for (int k = i - 1; k > 0; k--) {
                (dp[j + k] += dp[j]) %= MOD;
            }
        }
    }

    ll ans = 0;
    for (int i = 0; i <= K; i++) {
        (ans += dp[i]) %= MOD;
    }
    cout << ans << endl;
    return 0;
}