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A234825 Number of (n+1) X (1+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. 1

%I

%S 69,516,3843,28602,212850,1583955,11787201,87715899,652748544,

%T 4857507711,36147734568,268997764212,2001779586225,14896486309185,

%U 110854015040601,824933638413864,6138844024165119,45682954601641506,339955264040033718

%N Number of (n+1) X (1+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="/A234825/b234825.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 9*a(n-1) - 12*a(n-2) + 3*a(n-3).

%F Empirical g.f.: 3*x*(23 - 35*x + 9*x^2) / (1 - 9*x + 12*x^2 - 3*x^3). - _Colin Barker_, Oct 16 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 1 of A234832.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 31 2013

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Last modified September 24 21:51 EDT 2022. Contains 356949 sequences. (Running on oeis4.)