N, S, K = map(int, input().split())

mod = 10**9+7
S -= K*N*(N-1)//2
if S<0:
    print(0)
elif S==0:
    print(1)
else:
    dp = [0]*(S+1)
    dp[0] = 1
    for i in range(N,0,-1):
        ndp = [0]*(S+1)
        sm = [0]*i
        for j in range(S+1):
            sm[j%i] += dp[j]
            sm[j%i] %= mod
            ndp[j] += sm[j%i]
            ndp[j] %= mod
        dp = ndp
    print(dp[-1])