cp's OEIS Frontend

A268906 Number of 3 X n 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once.

%I A268906 #8 Jan 16 2019 15:53:47
%S A268906 0,240,1584,9720,54936,299088,1585800,8244288,42216696,213602256,
%T A268906 1070280936,5319700704,26262038232,128900271600,629516497608,
%U A268906 3061019061504,14827169463480,71576870716944,344483107968168
%N A268906 Number of 3 X n 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once.
%H A268906 R. H. Hardin, <a href="/A268906/b268906.txt">Table of n, a(n) for n = 1..210</a>
%F A268906 Empirical: a(n) = 10*a(n-1) - 29*a(n-2) + 20*a(n-3) - 4*a(n-4) for n>6.
%F A268906 Empirical g.f.: 24*x^2*(10 - 34*x + 35*x^2 - 47*x^3 + 37*x^4) / (1 - 5*x + 2*x^2)^2. - _Colin Barker_, Jan 16 2019
%e A268906 Some solutions for n=4:
%e A268906 ..1..0..0..2. .1..1..2..2. .0..1..0..1. .0..2..2..2. .0..1..2..2
%e A268906 ..0..1..2..2. .2..2..1..2. .2..1..2..1. .1..2..2..2. .2..1..0..1
%e A268906 ..2..1..2..1. .1..2..2..1. .2..2..0..0. .1..2..2..1. .0..1..0..0
%Y A268906 Row 3 of A268904.
%K A268906 nonn
%O A268906 1,2
%A A268906 _R. H. Hardin_, Feb 15 2016