There are 15 points in the line segment AB, if the midpoints of the line segment with these 17 points as endpoints are all colored red, what is the minimum number of red points on the line segment AB?
线段AB内有15个点，若以这17个点为端点的线段的中点都染上红色，则线段AB上最少有多少个红点．
<gadget id="calculator">15 + 16</gadget>
<output>31</output>

<result>31</result>