def solve():
    MOD = 10 ** 9 + 7

    N, S, K = list(map(int, input().split()))
    S -= K * N * (N - 1) // 2

    if S < 0:
        print(0)
        return

    dp = [0 for s in range(20101)]
    dp[0] = 1

    for i in range(N):
        for j in range(S + 1):
            dp[j] += dp[j - (N - i)]
            if dp[j] > MOD:
                dp[j] -= MOD

    print(dp[S])


if __name__ == '__main__':
    solve()