#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;

constexpr int P = 1000000007;

constexpr int N = 300, K = N * (N - 1) / 2;
int dp[N][K + 1];

int main() {
    int n, k;
    cin >> n >> k;

    dp[0][0] = 1;
    for (int i = 1; i < n; i++) {
        int k1 = min(k, (i + 1) * i / 2);
        int64_t t = 0;
        for (int j = 0; j <= k1; j++) {
            t += dp[i - 1][j];
            if (j - i - 1 >= 0) t -= dp[i - 1][j - i - 1];
            dp[i][j] = t % P;
        }
    }

    int64_t r = 0;
    for (int j = 0; j <= k; j++) {
        r += dp[n - 1][j];
    }
    r %= P;

    cout << r << endl;

    return 0;
}