求 0—7 所能組成的奇數個數

sum = 0
for i in range(1,9):
    if i == 1:
        n = 4
        sum += 4
    elif 1 < i< 3:
        sum += 7*n
    else:
        sum += 7*(8**(i-2))*n
print(sum)

# 法二：
sum = 4
s = 4
for j in range(2, 9):
    print(sum)
    if j <= 2:
        s *= 7
    else:
        s *= 8
    sum += s
print(f'sum = {sum}')