#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

#define REP(i, init, n) for(int i = (int)(init); i < (int)(n); i++)

#define vi vector<int>
#define vl vector<long>
#define vvi vector<vector<int>>
#define vvl vector<vector<long>>
#define pint pair<int, int>
#define plong pair<long, long>

int N, S, K;

void solve() {
    S -= K * (N - 1) * N / 2;
    if(S < 0) {
        cout << 0 << endl;
        return;
    }
    vvl dp(N + 1, vl(S + 1, 0));
    dp[0][0] = 1;
    REP(i, 1, N + 1) {
        int add = N + 1 - i;
        REP(j, 0, S + 1) {
            if(i == N) {
                dp[i][S] += dp[i - 1][j];
                dp[i][S] %= mod;
                continue;
            }
            int m = 0;
            while(j + add * m <= S) {
                dp[i][j + add * m] += dp[i - 1][j];
                dp[i][j + add * m] %= mod;
                m++;
            }
        }
    }
    cout << dp[N][S] << endl;
}

int main() {
    cin >> N >> S >> K;
    solve();
}