#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<set>
#include<map>
#include<vector>
#include<algorithm>
#include<queue>
#include<iostream>
using namespace std;

long long mod = 1000000007;
long long dp[2005][2005];

long long binpow(long long a, long long n)
{
	long long ans = 1;
	while(n > 0)
	{
		if(n & 1ll)
			ans = (ans * a) % mod;
		a = (a * a) % mod;
		n /= 2;
	}
	return ans;
}

int main()
{
	while(1)
	{
		long long n, d, x;
		scanf("%lld%lld%lld", &n, &d, &x);
		if(n == 0)
			break;

		int rd = min(n, d);
		memset(dp, 0, sizeof(dp));
		dp[0][0] = 1;
		for(int i = 1; i <= rd; i++)
			for(int j = 1; j <= n; j++)
				dp[j][i] = (dp[j - 1][i] + dp[j - 1][i - 1] + (j >= x ? mod - dp[j - x][i - 1] : 0)) % mod;
		
		long long ans = 0, cnk = 1;
		for(int i = 1; i <= rd; i++)
		{
			cnk = (((cnk * ((d - i + 1) % mod)) % mod) * binpow(i, mod - 2)) % mod;
			ans = (ans + cnk * dp[n][i]) % mod;
		}
		printf("%lld\n", ans);
	}

	return 0;
}
