Write a series of natural numbers 1, 2, ..., 98, 99 on the paper. One operation refers to crossing out the first three numbers in the sequence, and then writing the sum of these three numbers at the end of the sequence. For example, 4, 5, ..., 98, 99, 6 are obtained after the first operation; and 7, 8, ..., 98, 99, 6, 15 are obtained after the second operation. Going on like this, there will be only one number left in the end. What is the sum of all the numbers that appear on the paper with the first 99 numbers and the numbers written down later.
在纸上写着一列自然数1，2，…，98，99．一次操作是指将这列数中最前面的三个数划去，然后把这三个数的和写在数列的最后面．例如第一次操作后得到4，5，…，98，99，6；而第二次操作后得到7，8，…，98，99，6，15．这样不断进行下去，最后将只剩下一个数，最初的99个数连同后面写下的数，纸上出现的所有数的总和是多少．
<gadget id="calculator">1 + 99</gadget>
<output>100</output>

<gadget id="calculator">99 / 2</gadget>
<output>99/2 = around 49.5</output>

<gadget id="calculator">100 * (99/2)</gadget>
<output>4_950</output>

<gadget id="calculator">4_950 + 4_950 + 4_950 + 378 + 4_950 + 4_950</gadget>
<output>25_128</output>

<result>25_128</result>