A234826 - OEIS

%I #8 Oct 16 2018 07:56:29

%S 516,9207,161631,2826144,49366557,862112943,15054585588,262885602843,

%T 4590533340099,80160252775488,1399764282940233,24442786354729203,

%U 426821718006927396,7453191942015413679,130148180682091274007

%N Number of (n+1) X (2+1) 0..2 arrays with each 2 X 2 subblock having the number of clockwise edge increases less than or equal to the number of counterclockwise edge increases.

%H R. H. Hardin, <a href="/A234826/b234826.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 23*a(n-1) - 102*a(n-2) + 93*a(n-3) - 9*a(n-4).

%F Empirical g.f.: 3*x*(172 - 887*x + 834*x^2 - 81*x^3) / (1 - 23*x + 102*x^2 - 93*x^3 + 9*x^4). - _Colin Barker_, Oct 16 2018

%e Some solutions for n=3:

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

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

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

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

%Y Column 2 of A234832.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 31 2013