#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

struct mint {
	long long x;
	mint(long long x = 0) :x((x% mod + mod) % mod) {}
	mint& operator+=(const mint a) {
		if ((x += a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator-=(const mint a) {
		if ((x += mod - a.x) >= mod) x -= mod;
		return *this;
	}
	mint& operator*=(const mint a) {
		(x *= a.x) %= mod;
		return *this;
	}
	mint operator+(const mint a) const {
		mint res(*this);
		return res += a;
	}
	mint operator-(const mint a) const {
		mint res(*this);
		return res -= a;
	}
	mint operator*(const mint a) const {
		mint res(*this);
		return res *= a;
	}
	mint pow(ll t) const {
		if (!t) return 1;
		mint a = pow(t >> 1);
		a *= a;
		if (t & 1) a *= *this;
		return a;
	}

	// for prime mod
	mint inv() const {
		return pow(mod - 2);
	}
	mint& operator/=(const mint a) {
		return (*this) *= a.inv();
	}
	mint operator/(const mint a) const {
		mint res(*this);
		return res /= a;
	}
};

mint dp[2][90000];
void init(int x, int k) {
	for (int i = 0; i <= k + 1; i++) dp[x][i] = 0;
}
int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/

	int n, k; scanf("%d %d", &n, &k);
	dp[0][0] = 1;
	int cur = 0;
	int nxt = 1;
	for (int i = 1; i < n; i++) {
		init(nxt, k);
		for (int j = 0; j <= k; j++) {
			int lf = j;
			int rg = min(k, j + i);
			dp[nxt][lf] += dp[cur][j];
			dp[nxt][rg + 1] -= dp[cur][j];
		}
		for (int j = 0; j <= k; j++) dp[nxt][j + 1] += dp[nxt][j];
		swap(cur, nxt);
	}
	mint res = 0; for (int i = 0; i <= k; i++) res += dp[cur][i];
	cout << res.x << "\n";
	return 0;
}