import sys
import itertools
stdin=sys.stdin

ip=lambda: int(sp())
fp=lambda: float(sp())
lp=lambda:list(map(int,stdin.readline().split()))
sp=lambda:stdin.readline().rstrip()
Yp=lambda:print('Yes')
Np=lambda:print('No')

N, S, K = lp()
rest = (N - 1) * N //2 * K
S -= rest

mod = 10 ** 9 + 7

ans = 0

dp = [[ 0 for _ in range(S + 1)] for _ in range(N + 1)]
if S < 0:
    print(0)
    sys.exit()
dp[0][0] = 1
for i in range(1,N + 1):
    for j in range(0, S + 1):
        if (j - 1) >= 0:
            dp[i][j] = (dp[i - 1][j] + dp[i][j - i])%mod
        else:
            dp[i][j] = dp[i - 1][j]

print(dp[N][S])