#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
using namespace std;
typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
const ll mod = 1000000007;
typedef long double ld;
typedef complex<ld> Point;
const ll INF = mod * mod;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
const ld eps = 1e-6;
const ld pi = acos(-1.0);
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;

//3281

const int mn = 3334;
//num
ll dp1[101][mn];
//sum
ll dp2[101][mn];
void solve() {
	int n, m; cin >> n >> m;
	dp1[0][0] = 1;
	rep(i, n) {
		int c = n - i;
		rep(j, mn) {
			if (dp1[i][j] == 0)continue;
			rep(k, m + 1) {
				if (k > c) {
					dp1[i + 1][j] += dp1[i][j];
					if (dp1[i + 1][j] >= mod)dp1[i + 1][j] -= mod;
					dp2[i + 1][j] = (dp2[i + 1][j] + dp2[i][j]+dp1[i][j] * k) % mod;
				}
				else {
					int z = j + k;
					int d = z / c;
					dp1[i + 1][d+j] += dp1[i][j];
					if (dp1[i + 1][d + j] >= mod)dp1[i + 1][d + j] -= mod;
					dp2[i + 1][d + j] = (dp2[i + 1][d + j] + dp2[i][j] + dp1[i][j] * k) % mod;
				}
			}
		}
	}
	ll ans = 0;
	rep(i, mn) {
		ll csum = dp2[n][i] - dp1[n][i] * i;
		csum = (csum%mod + mod) % mod;
		ans = (ans + csum) % mod;
	}
	cout << ans << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	solve();
	//stop
	return 0;
}