MOD = 10**9 + 7
N, S, K = map(int, input().split())

min_donation = (N - 1) * K * N // 2
if min_donation > S:
    print(0)
    exit(0)
elif min_donation == S:
    print(1)
    exit(0)

S -= min_donation
dp = [0] * (S + 1)
dp[0] = 1
for i in range(N):
    for j in reversed(range(S + 1)):
        a = 1
        while j + a * (N - i) < S + 1:
            dp[j + a * (N - i)] += dp[j]
            dp[j + a * (N - i)] %= MOD
            a += 1
print(dp[S])