cp's OEIS Frontend

A221727 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.

%I A221727 #6 Jul 23 2025 02:08:13
%S A221727 4,52,540,6188,71310,824144,9525048,110070012,1271809066,14694217628,
%T A221727 169767833676,1961352594276,22659537510670,261784302805272,
%U A221727 3024367348612856,34940131867655732,403658398327592910
%N A221727 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.
%C A221727 Column 4 of A221728
%H A221727 R. H. Hardin, <a href="/A221727/b221727.txt">Table of n, a(n) for n = 1..29</a>
%e A221727 Some solutions for n=3
%e A221727 ..0..2..2..0....2..0..0..2....0..0..2..2....2..2..0..0....0..2..0..2
%e A221727 ..0..0..0..2....2..2..2..2....0..2..2..2....2..2..2..0....0..2..2..0
%e A221727 ..2..2..2..0....0..0..0..0....2..0..0..0....0..0..2..0....2..0..0..2
%K A221727 nonn
%O A221727 1,1
%A A221727 _R. H. Hardin_ Jan 22 2013