There is a series of natural numbers, the latter number is twice the previous number, and the largest one is 128. What is the maximum sum of this series of numbers?
有一串自然数，后一个数是前一个数的2倍，其中最大的一个是128．这一串数的和最大是多少．
<gadget id="calculator">1 + 2 + 4 + 8 + 16 + 32 + 64 + 128</gadget>
<output>255</output>

<result>255</result>