n,s,k=map(int,input().split());mod=10**9+7
for i in range(n):
	s-=k*i
if s<0:
	print(0)
else:
	dp=[[0]*(s+1) for i in range(n+1)]
	dp[0][0]=1
	for i in range(n):
		c=n-i
		for j in range(s+1):
			for l in range(j,s+1,c):
				dp[i+1][l]+=dp[i][j]
				dp[i+1][l]%=mod
	print(dp[n][s])