#include <bits/stdc++.h>
using namespace std;

int sum[20210] = {};
int dp[110][20110];
int N,S,K;
vector<int> v;
int dfs(int x,int s){
	if( s < 0 ) return 0;
	if( dp[x][s] != -1 ) return dp[x][s];
	if( x == 0 ){
		return s == 0;
	}
	int ans = 0;
	for(int i = 0 ; ; i++){
		int c = i * x;
		if( c > s ) break;
		ans += dfs(x-1,s-c); 
		ans %= 1000000007;
	}
	return dp[x][s] = ans;
}



int main(){
	cin >> N >> S >> K;
	S -= K*N*(N-1)/2;
	if( S < 0 ) cout << 0 << endl;
	else{	
		dp[N][S] = 1;
		for(register int x = N ; x >= 1 ; x--){
			for(register int s = 0 ; s <= S ; s++){
				if( dp[x][s] == 0 ) continue;
				register int c = 0;
				register int C = dp[x][s];
				for(int k = 0 ; c <= s ; k++){
					if( c > s ) break;
					dp[x-1][s-c] += C;
					if( dp[x-1][s-c] >= 1000000007 ) dp[x-1][s-c] -= 1000000007;
					c += x;
				}
			}
		}
		cout << dp[0][0] << endl;
	}
	
}