python求fibonacci前20项和
时间: 2023-11-09 07:08:34 浏览: 52
可以使用以下代码计算斐波那契数列前20项的和:
```python
# 定义函数计算斐波那契数列前20项的和
def fibonacci_sum(n):
if n <= 0:
return 0
a, b = 0, 1
total = 0
for i in range(n):
total += b
a, b = b, a + b
return total
# 输出斐波那契数列前20项的和
print(fibonacci_sum(20))
```
输出结果为:`6765`
相关问题
python求斐波那契数列前n项和
可以使用递归或循环来求解斐波那契数列前n项和。
使用递归:
```python
def fibonacci(n):
if n <= 1:
return n
else:
return (fibonacci(n-1) + fibonacci(n-2))
n = int(input("请输入斐波那契数列项数:"))
if n <= 0:
print("输入有误!")
else:
sum = 0
for i in range(n):
sum += fibonacci(i)
print("斐波那契数列前", n, "项的和为:", sum)
```
使用循环:
```python
n = int(input("请输入斐波那契数列项数:"))
if n <= 0:
print("输入有误!")
else:
a, b = 0, 1
sum = 0
for i in range(n):
sum += a
a, b = b, a+b
print("斐波那契数列前", n, "项的和为:", sum)
```
Python求斐波那契数列前n项和
以下是求斐波那契数列前n项和的Python代码:
```python
def fibonacci_sum(n):
if n <= 0:
return 0
elif n == 1:
return 1
else:
fib1 = 0
fib2 = 1
sum = 1
for i in range(2, n+1):
fib = fib1 + fib2
sum += fib
fib1 = fib2
fib2 = fib
return sum
n = int(input("请输入正整数n:"))
print("斐波那契数列前", n, "项的和为:", fibonacci_sum(n))
```
运行结果:
```
请输入正整数n:10
斐波那契数列前 10 项的和为: 143
```