#include <iostream>
#include <vector>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
#define repeat_reverse(i,n) for (int i = (n)-1; (i) >= 0; --(i))
using namespace std;
const int mod = 1e9+7;
int main() {
    int n, s, k; cin >> n >> s >> k;
    s -= k * (n-1)*n/2;
    if (s < 0) {
        cout << 0 << endl;
    } else {
        vector<int> dp(s+1);
        dp[0] = 1;
        repeat (i,n) {
            repeat_reverse (j,s+1) {
                for (int a = 1; j + a*(n-i) < s+1; ++ a) {
                    dp[j + a*(n-i)] += dp[j];
                    dp[j + a*(n-i)] %= mod;
                }
            }
        }
        cout << dp[s] << endl;
    }
    return 0;
}