OFFSET
0,2
COMMENTS
Periodic with period 14.
The two ants are caught in a repeating cycle where they build and then erase a pattern of black cells, alternating between facing "northwards" and "southwards" on the completely white grid.
LINKS
Felix Fröhlich, Illustration of iterations 0-14 of the ants, 2019.
FORMULA
Conjectures from Colin Barker, Jul 11 2019: (Start)
G.f.: 2*x*(1 + x)*(1 - x + x^2)*(1 + x^2)^2*(1 + x^4) / ((1 - x)*(1 - x + x^2 - x^3 + x^4 - x^5 + x^6)*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6)).
a(n) = a(n-1) - a(n-2) + a(n-3) - a(n-4) + a(n-5) - a(n-6) + a(n-7) - a(n-8) + a(n-9) - a(n-10) + a(n-11) - a(n-12) + a(n-13) for n>12.
(End)
EXAMPLE
See illustrations in Fröhlich, 2019.
CROSSREFS
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Jul 10 2019
STATUS
approved