N,S,K=map(int,raw_input().split())
S-=K*N*(N-1)/2
if S < 0:
    print 0
    exit()

dp=[[[0 for i in range(S+1)] for j in range(S+1)] for k in range(2)]
mod=1000000007
dp[0][0][0]=1

for ni in range(1,N+1):
    for cur in range(S+1):
        for tot in range(S+1):
            if cur>tot:
                dp[ni%2][cur][tot]=0
                continue
            dp[ni%2][cur][tot]=dp[1-(ni%2)][cur][tot-cur]
            if cur >0:
                dp[ni%2][cur][tot] += dp[ni%2][cur-1][tot-1]
            dp[ni%2][cur][tot]%=mod 
            #if dp[ni%2][cur][tot]!=0:
            #    print ni, cur, tot, ":", dp[ni%2][cur][tot]

ans=0
for i in range(S+1):
    #print i, dp[N%2][i][S]
    ans+=dp[N%2][i][S]
    ans%=mod
print ans