迭代实现如下：

def fab(n):        n1 = 1        n2 = 1        if n<1:                print("输入有误!")                return -1        while (n-2)>0:                n3 = n2+n1                n1 = n2                n2 = n3                n-=1        return n3number = int(input("请输入要求的斐波那契数的第几个数:"))result = fab(number)print(result)

递归实现如下：

def fab(n):    if n==1 or n==2:        f = 1    else:        f = fab(n-1)+fab(n-2)    return fnumber = int(input("请输入要求的斐波那契数的第几个数:"))result = fab(number)print(result)