题解 | #等差数列#
等差数列
http://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
def funs(ao,d,n):
an = ao + (n-1)*d
return (ao+an)*n//2
while True:
try:
a = int(input())
b = funs(2,3,a)
print(b)
except:
break
an = ao + (n-1)*d
return (ao+an)*n//2
while True:
try:
a = int(input())
b = funs(2,3,a)
print(b)
except:
break
