# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from itertools import *
from functools import *
import sys
input = sys.stdin.readline
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
    
    X = [[] for _ in range(m)]
    for j in range(T+1):
        X[j%m].append(dp[i][j])
        
    for j in range(m):
        X[j] = list(accumulate(X[j]))
    
    for j in range(T+1):
        
        s,t = divmod(j,m)
        dp[i+1][j] = X[t][s] 
        dp[i+1][j] %= mod

print(dp[-1][T])