cp's OEIS Frontend

A268776 Number of n X 3 binary arrays with some element plus some horizontally, vertically, diagonally or antidiagonally adjacent neighbor totalling two no more than once.

%I A268776 #8 Jan 15 2019 09:10:26
%S A268776 7,26,91,316,1031,3354,10615,33344,103339,317958,970515,2945172,
%T A268776 8888719,26705714,79909167,238257768,708129267,2098664158,6203795403,
%U A268776 18296271036,53845375703,158159174410,463734769895,1357486034320,3967761581627
%N A268776 Number of n X 3 binary arrays with some element plus some horizontally, vertically, diagonally or antidiagonally adjacent neighbor totalling two no more than once.
%H A268776 R. H. Hardin, <a href="/A268776/b268776.txt">Table of n, a(n) for n = 1..210</a>
%F A268776 Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - 16*a(n-3) - a(n-4) + 12*a(n-5) - 4*a(n-6).
%F A268776 Empirical g.f.: x*(7 - 2*x - 27*x^2 + 12*x^3 + 8*x^4 - 4*x^5) / (1 - 2*x - 3*x^2 + 2*x^3)^2. -  _Colin Barker_, Jan 15 2019
%e A268776 Some solutions for n=4:
%e A268776 ..0..1..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..0
%e A268776 ..0..1..0. .0..1..1. .1..0..0. .0..0..0. .0..0..1. .0..1..0. .0..1..0
%e A268776 ..0..0..0. .0..0..0. .0..0..1. .0..0..1. .1..0..0. .0..0..0. .0..0..0
%e A268776 ..0..1..0. .0..1..0. .0..1..0. .1..0..0. .1..0..0. .0..0..1. .1..0..0
%Y A268776 Column 3 of A268781.
%K A268776 nonn
%O A268776 1,1
%A A268776 _R. H. Hardin_, Feb 13 2016