A231257 - OEIS

%I #8 Feb 16 2018 09:36:13

%S 3,15,89,547,3381,20911,129329,799835,4946509,30591143,189187465,

%T 1170008467,7235785189,44748896799,276744502881,1711495152971,

%U 10584548667901,65458946997783,404823472069561,2503585087356803

%N Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with values 0..2 introduced in row major order.

%C Column 2 of A231263.

%H R. H. Hardin, <a href="/A231257/b231257.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 10*a(n-1) -29*a(n-2) +36*a(n-3) -16*a(n-4).

%F Empirical g.f.: x*(1 - 2*x)*(3 - 9*x + 8*x^2) / ((1 - x)*(1 - 9*x + 20*x^2 - 16*x^3)). - _Colin Barker_, Feb 16 2018

%e Some solutions for n=3:

%e ..0..0..0....0..0..1....0..0..1....0..0..0....0..0..1....0..0..1....0..0..0

%e ..0..0..1....0..1..2....0..1..2....0..0..0....0..1..2....0..1..0....1..1..1

%e ..0..1..1....1..2..0....1..2..2....0..0..0....1..2..1....1..0..0....0..0..2

%e ..1..1..1....2..0..0....2..2..2....0..0..0....2..1..1....0..0..0....0..2..2

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 06 2013