题解 | #尼科彻斯定理#

while True:
    try:
        num = int(input())
        s = 1
        t = []
        for i in range(num):
            s = s + 2 * i 
        t.append(str(s))
        for i in range(num-1):
            s = s+2
            t[0] = t[0] + '+' + str(s)
        print(t[0])
    except:
        break

第一个奇数为1 + 2X0 + 2X1 + … + 2X(num-1)