# 1つ前の生徒との差分を xiとする
# x1 + x1+x2+K + x1+x2+K+x3+K + x1+x2+x3+2K+x4+K + ... = S
# <=> Nx1 + (N-1)x2 + (N-2)x3 + ... + xN + K*N(N-1)/2 = S


N, S, K = map(int, input().split())
mod = 10**9 + 7
S -= K*N*(N-1)//2
if S < 0:
    print(0)
    quit()

dp = [0] * (S+1)
dp[0] = 1
for i in range(N):
    c = N - i
    nex = [0] * (S+1)
    for j in range(S+1):
        for jj in range(0, S+1, c):
            if j + jj > S:
                break
            nex[j+jj] += dp[j]
            nex[j+jj] %= mod
    dp = nex

print(dp[-1])