#include <bits/stdc++.h>

namespace Initial {
	#define ll long long
	#define ull unsigned long long
	#define fi first
	#define se second
	#define mkp make_pair
	#define pir pair <int, int>
	#define pb push_back
	#define i128 __int128
	using namespace std;
	const ll maxn = 155, inf = 1e9, mod = 1e9 + 7;
	ll power(ll a, ll b = mod - 2) {
		ll s = 1;
		while(b) {
			if(b & 1) s = 1ll * s * a %mod;
			a = 1ll * a * a %mod, b >>= 1;
		} return s;
	}
	template <class T>
	const inline ll pls(const T x, const T y) { return x + y >= mod? x + y - mod : x + y; }
	template <class T>
	const inline void add(T &x, const T y) { x = x + y >= mod? x + y - mod : x + y; }
	template <class T>
	const inline void chkmax(T &x, const T y) { x = x < y? y : x; }
	template <class T>
	const inline void chkmin(T &x, const T y) { x = x > y? y : x; }
} using namespace Initial;

namespace Read {
	char buf[1 << 22], *p1, *p2;
//	#define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, (1 << 22) - 10, stdin), p1 == p2)? EOF : *p1++)
	template <class T>
	const inline void rd(T &x) {
		char ch; bool neg = 0;
		while(!isdigit(ch = getchar()))
			if(ch == '-') neg = 1;
		x = ch - '0';
		while(isdigit(ch = getchar()))
			x = (x << 1) + (x << 3) + ch - '0';
		if(neg) x = -x;
	}
} using Read::rd;

ll n, m, f[maxn][maxn * maxn / 2][2], ans, a[maxn * maxn / 2];

signed main() {
	rd(n), rd(m); ll P = n * (n + 1) / 2;
	for(ll s = 1; s <= m; s++) {
		memset(f, 0, sizeof f);
		f[s][0][0] = mod - 1, f[s][0][1] = (mod - 1) * (s - 1) %mod;
		for(ll i = s, lim = 0; i < n; lim += i - s, i++) {
			for(ll j = 0; j <= lim; j++)
				for(ll k = i + 1; k <= n; k++) {
					if(i < m && k > m) break;
					add(f[k][j + (((k - i) * (k - i - 1)) >> 1)][0], mod - f[i][j][0]);
					add(f[k][j + (((k - i) * (k - i - 1)) >> 1)][1],
					 (mod - f[i][j][0]) * (k - i - 1) %mod);
					add(f[k][j + (((k - i) * (k - i - 1)) >> 1)][1], mod - f[i][j][1]);
				}
		}
		for(ll i = m, lim = (i - s) * (i - s - 1) / 2; i <= n; lim += i - s, i++)
			for(ll j = 0; j <= lim; j++)
				add(a[j + s * (n - i + 1) + s * (s - 1) / 2 + (n - i)
				 * (n - i + 1) / 2], (f[i][j][1] + f[i][j][0] * (n - i)) %mod);
	}
	for(ll i = 0; i < P; i++)
		add(ans, P * power(P - i) %mod * a[i] %mod);
	printf("%lld\n", ans * power(n - 1) %mod);
	return 0;
}