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

if D < 0:
    print(0)
    sys.exit()
elif D == 0:
    print(1)
    sys.exit()

mod = 10 ** 9 + 7

from functools import lru_cache
@lru_cache(maxsize=None)
def dfs(a, x):  # a:割り振り数、b:min数、x:残り人数、返り値パターン数%mod
    global mod
    ans = 0
    if x == 2:
        return a//2 + 1
    for i in range(a // x + 1):
        ans = (ans + dfs(a - i * x, x - 1)) % mod
    #print(a,b,x,ans)
    return ans


print(dfs(D, N))