Y by Mango247
Some
lamps are cyclically connected: lamp
with lamp
, ... , lamp
with
, ... , lamp
with lamp
. At the beginning, all lamps are off. When one pushes the switch of a lamp, that lamp and the two ones connected to it change status (from off to on, or vice-versa). Determine the number of configurations of lamps reachable from the initial one, through some set of switches being pushed.






