Yeah, that's not a very interesting definition of the state. Try the one I described.
So if the angel and devil are approaching lantern 5, the state would be the state of lantern 5, followed by the state of lantern 6,..., ending with the state of lantern 4.
This would be equivalent to cyclically bit shifting the binary number so the next lantern the angel and devil will visit is at the front.
Say there are 5 lanterns: 1 is on, 2 is on, 3 is off, 4 is off, 5 is off. If the angel and devil are approaching lantern 4, the state is 00110. This is because looking forward from the pair's position they see off,off,on,on,off.