题解 | #等差数列#
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
def sum_func(n, a = 2):
sum = a *n + 3 * n * (n - 1) / 2
return int(sum)
while True:
try:
input_num = int(input())
print(sum_func(input_num))
except:
break
记住等差数列的计算公式,定义函数,然后输出即可。

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