我就废话不多说了，直接上代码吧！

#!/usr/bin/env python# coding:UTF-8 """@version: python3.x@author:曹新健@contact: 617349013@qq.com@software: PyCharm@file: 1223.py@time: 2018/12/23 20:56""" '''有一分数序列：2/1，3/2，5/3，8/5，13/8，21/13...求出这个数列的前20项之和。'''"""#方法一def g(n): if n <= 2: return n else: return g(n-1) + g(n-2)sum = 0for i in range(1,21): sum += g(i+1)/g(i)print(sum)""" #方法二numerator = 2denominator = 1sum = 0while True: try: n = int(input("请输入一个整数：")) except ValueError: print("输入错误，请输入整数") else: for i in range(n): sum += numerator / denominator numerator, denominator = numerator + denominator, numerator print(sum) break

补充拓展：Python分数加法的实现

或多或少大家都会觉得用电脑计算器不能显示分数很麻烦，所以用Python做一个分数加法是极好的

a = input()b = a.split(',') def eu(a,b): if a < b: a, b = b, a r = 1 while r != 0: r = a % b a = b b = r return a num1 = b[0].split('/')num2 = b[1].split('/')sum1 = int(num1[0])*int(num2[1]) + int(num2[0])*int(num1[1])sum2 = int(num1[1])*int(num2[1])GCD = eu(sum1,sum2) c = int(sum1/GCD)d = int(sum2/GCD) if c%d == 0: print(int(c/d))else: print(str(c)+ '/'+str(d))

实际上用fractions模块可以瞬间解决问题

from fractions import Fractiona,b = (input().split(','))sum=Fraction(a)+Fraction(b)print(sum)

以上这篇Python实现分数序列求和就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。