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

typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<vector<long long>> VVL;
typedef pair<int,int> Pair;
typedef tuple<int,int,int> tpl;

#define ALL(a)  (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define REVERSE(c) reverse((c).begin(),(c).end())
#define EXIST(m,v) (m).find((v)) != (m).end()
#define LB(a,x) lower_bound((a).begin(), (a).end(), x) - (a).begin()
#define UB(a,x) upper_bound((a).begin(), (a).end(), x) - (a).begin()

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RFOR(i,a,b) for(int i=(a)-1;i>=(b);--i)
#define RREP(i,n) RFOR(i,n,0)

#define en "\n"

constexpr double EPS = 1e-9;
constexpr double PI  = 3.1415926535897932;
constexpr int INF = 2147483647;
constexpr long long LINF = 1LL<<60;
constexpr long long MOD = 1000000007; // 998244353;

template<class T> inline bool chmax(T& a, T b){if(a<b){a=b;return true;}return false;}
template<class T> inline bool chmin(T& a, T b){if(a>b){a=b;return true;}return false;}

void add(int& a, int b){
    a += b;
    if(a>=MOD) a -= MOD;
    return;
}

void Main(){
    int N,S,K; cin >> N >> S >> K;
    int M = S - K*N*(N-1)/2;
    if(M<0){
        cout << 0 << en;
        return;
    }
    int dp[N+1][M+1]; REP(i,N+1)REP(j,M+1) dp[i][j] = 0;
    dp[0][0] = 1;
    REP(i,N)REP(j,M+1){
        if(dp[i][j] == 0) continue;
        add(dp[i+1][j], dp[i][j]);
        FOR(ai,1,M+1){
            int to = j+ai*(N-i);
            if(to>M) break;
            add(dp[i+1][to], dp[i][j]);
        }
    }

    int ans = dp[N][M];
    cout << ans << en;
    return;
}

int main(void){
    cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);cout<<fixed<<setprecision(15);
    int t=1; //cin>>t;
    while(t--) Main();
    return 0;
}