import sys

sys.setrecursionlimit(10 ** 6)
def MI(): return map(int, sys.stdin.readline().split())

class mint:
    def __init__(self, x):
        self.__x = x % md

    def __str__(self):
        return str(self.__x)

    def __add__(self, other):
        if isinstance(other, mint): other = other.__x
        return mint(self.__x + other)

    def __sub__(self, other):
        if isinstance(other, mint): other = other.__x
        return mint(self.__x - other)

    def __rsub__(self, other):
        return mint(other - self.__x)

    def __mul__(self, other):
        if isinstance(other, mint): other = other.__x
        return mint(self.__x * other)

    __radd__ = __add__
    __rmul__ = __mul__

    def __truediv__(self, other):
        if isinstance(other, mint): other = other.__x
        return mint(self.__x * pow(other, md - 2, md))

    def __pow__(self, power, modulo=None):
        return mint(pow(self.__x, power, md))

md=10**9+7
def main():
    n,s,k=MI()
    dp=[[0]*(s+1) for _ in range(n+1)]
    # dp[i][j]...i人でj円を払う方法の数
    for j in range(s+1):dp[1][j]=mint(1)
    for i in range(2,n+1):
        for j in range(s+1):
            v=0
            for a in range((j - k * i * (i - 1) // 2) // i + 1):
                v += dp[i - 1][j - a * i - k * (i - 1)]
            dp[i][j]=v
    print(dp[n][s])

main()