cp's OEIS Frontend

A221729 Number of 3Xn 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 A221729 #6 Jul 23 2025 02:08:28
%S A221729 0,16,0,540,0,22180,0,911081,0,37357844,0,1530451369,0,62678117602,0,
%T A221729 2566608259733,0,105095354454990,0,4303284726664321,0,
%U A221729 176203240002820998,0,7214839389152381265,0,295419432979789366510,0,12096265452242634926017
%N A221729 Number of 3Xn 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 A221729 Row 3 of A221728
%H A221729 R. H. Hardin, <a href="/A221729/b221729.txt">Table of n, a(n) for n = 1..32</a>
%e A221729 Some solutions for n=4
%e A221729 ..0..2..0..0....2..0..2..0....2..0..2..0....2..2..2..0....2..0..0..2
%e A221729 ..0..2..2..0....0..2..2..0....0..2..0..0....0..0..0..2....2..2..2..2
%e A221729 ..2..2..0..2....2..0..2..0....0..2..2..2....2..0..0..2....0..0..0..0
%K A221729 nonn
%O A221729 1,2
%A A221729 _R. H. Hardin_ Jan 22 2013