MathDB

Four orange lights are located at the points

(2,0)

(4,0)

(6,0)

and

(8,0)

in the

xy

-plane. Four yellow lights are located at the points

(1,0)

(3,0)

(5,0)

(7,0)

. Sparky chooses one or more of the lights to turn on. In how many ways can he do this such that the collection of illuminated lights is symmetric around some line parallel to the

y

-axis?
Proposed by Evan Chen

Problem Statement