# coding: utf-8
import array, bisect, collections, copy, heapq, itertools, math, random, re, string, sys, time

sys.setrecursionlimit(10 ** 7)
INF = 10 ** 20
MOD = 10 ** 9 + 7


def II(): return int(input())
def ILI(): return list(map(int, input().split()))
def IAI(LINE): return [ILI() for __ in range(LINE)]
def IDI(): return {key: value for key, value in ILI()}


def read():
    N, S, K = ILI()
    return (N, S, K)


def solve(N, S, K):
    S -= K * N * (N - 1) // 2
    if S < 0:
        return 0

    dp = [[0] * (S + 1) for __ in range(N + 1)]
    for i in range(S // N + 1):
        dp[1][i * N] = 1
    for i in range(2, N + 1):
        t = N - i + 1
        for j in range(S + 1):
            dp[i][j] += dp[i - 1][j]
            if j - t >= 0:
                dp[i][j] += dp[i][j - t]

    ans = dp[N][S] % MOD
    return ans


def main():
    params = read()
    print(solve(*params))


if __name__ == "__main__":
    main()