Python斐波那契数列

while 1:
    def fib(n):
        if n == 1 or n == 2:
            return 1
        return fib(n - 1) + fib(n - 2)
    
    
    n = int(input('请输入所求数的索引：\n'))
    if n == -1:  # 设置跳出循环的条件
        break
    print('索引为%s的斐波那契数列为%s' % (n, fib(n)))