#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;

const int MM = 1e9 + 7;
const double eps = 1e-8;
const int MAXN = 2e6 + 10;

int n, m;

void prework(){

}

void read(){

}

int f[302][50000];
void upd(int &x, int y){
	x += y;
	if (x >= MM) x -= MM;
}

void solve(int casi){
//	cout << "Case #" << casi << ": ";
	cin >> n >> m;
	f[1][0] = 1;
	f[2][0] = 1; f[2][1] = 1;
	// f[p][q] p ge shu, nixudui wei q
	for (int i = 3; i <= n; i++){
		int p = (i - 2) * (i - 1) / 2;
		int q = (i - 1) * i / 2;
		int tmp = 0;
		for (int k = 0; k < i; k++){
			upd(tmp, f[i-1][k]);
			f[i][k] = tmp;
		}
		for (int j = i; j <= q; j++){
			upd(tmp, f[i-1][j]);
			tmp -= f[i-1][j-i];
			if (tmp < 0) tmp += MM;
			f[i][j] = tmp;
		}
		
		/*
		for (int j = 0; j <= p; j++){
			for (int k = 0; k < i; k++)
				upd(f[i][j + k], f[i - 1][j]);
		}*/
	}
	int ans = 0;
	for (int i = 0; i <= m; i++)
		upd(ans, f[n][i]);
	cout << ans << endl;
}

void printans(){

}


int main(){
//	std::ios::sync_with_stdio(false);
	prework();
	int T = 1;
//	cin>>T;
	for(int i = 1; i <= T; i++){
		read();
		solve(i);
		printans();
	}
	return 0;
}