import java.util.*;

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int kk = sc.nextInt();
        int[][] dp = new int[n + 1][n * (n + 1) / 2 + 1];
        dp[1][0] = 1;
        for (int i = 2; i <= n; i++) {
            for (int j = 0; j <= i * (i - 1) / 2; j++) {
                for (int k = 0; k < i; k++) {
                    dp[i][j + k] += dp[i - 1][j];
                    dp[i][j + k] %= MOD;
                }
            }
        }
        long total = 0;
        for (int i = 0; i <= kk; i++) {
            total += dp[n][i];
            total %= MOD;
        }
        System.out.println(total);
    }
}