OFFSET
1,1
COMMENTS
An explanation of the Hensel notation used to define the cellular automaton rule can be found on the LifeWiki (see links).
Lines of odd lengths are excluded because they break up into patterns not consisting of diagonal lines.
These diagonal line oscillators are effectively emulating a four-state one-dimensional cellular automaton.
From Charlie Neder, Feb 12 2019: (Start)
Specifically, such an oscillator with 2*n cells is isomorphic to a row of 2*n state-1 cells that evolve according to the following rules:
1) A state-1 cell becomes state-3 if it has a state-1 neighbor, and state-2 otherwise,
2) A state-2 cell becomes state-1 unconditionally,
3) A state-3 cell becomes state-1 if both its neighbors are state-3, and state-2 otherwise. (End)
FORMULA
If n == 2 (mod 4), a(n) = 3.
EXAMPLE
a(4) = 5 because a diagonal line of 8 cells oscillates with period 5 in this cellular automaton.
CROSSREFS
KEYWORD
nonn
AUTHOR
WG Zeist, Jan 12 2019
STATUS
approved