#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
#include <sstream>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////
const LL mod=(int)1e9+7;
LL dp[20001];
int N,S,K;

LL solve(){
	rep(i,N){
		if(i != N-1){
			for(int zan=1;zan <= S;++zan){
				if( dp[zan] ){
					for(int k=1; k*(N-i) <= zan; ++k){
				dp[ zan-k*(N-i) ] = (dp[ zan-k*(N-i) ] + dp[zan])%mod;
					}
				}
			}
		}
		else{
			for(int zan=1;zan <= S;++zan){
				dp[0] = (dp[0] + dp[zan] )%mod;
			}
		}
	}
	return dp[0];
}

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    //cout << setprecision(16);//

	
	cin>>N>>S>>K;
	S -=K*N*(N-1)/2;
	if(S < 0){
		P(0);
		return 0;
	}else if(S==0){
		P(1);
		return 0;
	}
	LL ans;
	dp[S] = 1;
	ans = solve();
	P(ans);
	return 0;
}