#include<bits/stdc++.h>
#include<atcoder/all>
//#include<atcoder/modint>
using namespace std;
using namespace atcoder;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> inline bool chmin(T &a, T b) { return ((a>b) ? (a = b, true) : (false));}
#define rep(i,s,n) for(long long i=s;i<(long long)(n);i++)
#define rrep(i,s,n) for(long long i=n-1;i>=s;i--)
const long long inf = 1LL<<60;
typedef long long ll;
#define cmp [](pair<ll,ll> a, pair<ll,ll> b){return a.second<b.second;} //pairのsecondでソートsort(p.begin(),p.end(),cmp)
typedef pair<long long, long long> P;
typedef pair<ll, pair<ll,ll> > PP;
#define rll ll,vector<ll>,greater<ll>
#define rP P,vector<P>,greater<P>
const long double pi = 3.14159265358979;
typedef unsigned long long ull;

using mint = modint1000000007;

int main()
{
    ll n,s,k; cin >> n >> s >> k;
    ll rest = s - (n-1)*n*k/2;
    if(rest < 0) {
        cout << 0 << endl;
        return 0;
    } else if(rest == 0) {
        cout << 1 << endl;
        return 0;
    }
    mint dp[n+1][rest+1];
    dp[0][rest] = 1;
    rep(i,1,n+1) {
        rep(j,0,rest+1) {
            for(ll k=j;k>=0;k-=i) {
                dp[i][k] += dp[i-1][j];
            }
        }
    }
    cout << dp[n][0].val() << endl;
}