import sys
input=lambda: sys.stdin.readline().rstrip()
n,s,k=map(int,input().split())
mod=10**9+7
import copy
s-=n*(n-1)//2*k
if s<0:
  print(0)
else:
  DP=[[0]*(s+1) for _ in range(n+1)]
  for i in range(s+1):
    DP[1][i]=1
  for i in range(2,n+1):
    for j in range(s+1):
      ct=0
      while j-ct*i>=0:
        DP[i][j]+=DP[i-1][j-ct*i]
        if DP[i][j]>mod:
          DP[i][j]%=mod
        ct+=1
  print(DP[n][s])