N,S,K = map(int,input().split())
mod = 10**9 + 7

T = S - K*N*(N-1)//2
if T < 0:
    print(0)
    exit()

dp = [[0]*(T+2) for _ in range(N+1)]
dp[0][0] = 1
for i in range(N):
    
    m = N - i
    
    for j in range(T+1):
        
        for k in range(j,T+1,m):
            
            dp[i+1][k] += dp[i][j]
            dp[i+1][k] %= mod

print(dp[-1][T])