Python如何写求下列式子的代码？

Question

s=1+(1+2)+(1+2+3)+...+(1+2+3+...+n)

Answer 1

n = int(input("输入n: "))
s = 0
for i in range(1,n+1):
    s += sum(range(1,i+1))
print("和 = {}".format(s))