import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.HashMap;
import java.util.StringTokenizer;

public class Main
{
	static final int mod = 1000*1000*1000 + 7;
	static int dp[][];
	static int n,s,k;
	public static int solve(int ind,int s) {
		//System.out.println(s);
		if (s < 0) {
			return 0;
		}
		if (ind == n) {
			return  s == 0 ? 1 : 0;
		}
		if (dp[ind][s] != -1) {
			return dp[ind][s];
		}
		int ret = 0;
		ret += solve(ind + 1,s);
		ret %= mod;
		ret += solve(ind,s - (n - ind));
		ret %= mod;
		return dp[ind][s] = ret;
	}
	public static void main(String[]args) throws Throwable {
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();  s = sc.nextInt(); k = sc.nextInt();
		dp = new int[n][s];
		for (int i = 0 ; i < n ; ++i) {
			s -= i * k;
		}
		for (int i = 0 ; i < n ; ++i) {
			Arrays.fill(dp[i], -1);
		}
		System.out.println(solve(0,s));
	}

	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream s) {
			br = new BufferedReader(new InputStreamReader(s));
		}

		public Scanner(String s) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(new File(s)));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		public boolean ready() throws IOException {
			return br.ready();
		}
	}
}