def problem203():
	squarefree = set()
	for n in range(1,51):
		for k in range(1, n//2 + 1):
			if isSquareFree(nCk(n,k)):
				squarefree.add(nCk(n,k))
	return sum(squarefree) + 1
def problem148():
	n = 2*7**2 + 3*7 + 5
	print(divisible7(n))
	total = 0
	for k in range(0,n+1):
		if nCk(n,k) % 7 == 0:
			print(k, base7(k))
	return
	for n in range(1,101):
		total += solutions(n)
	return total