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Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
1

%I #4 Aug 15 2018 13:09:04

%S 1,5,18,67,249,925,3437,12770,47447,176289,655001,2433653,9042226,

%T 33596347,124827065,463794357,1723225693,6402636738,23788965871,

%U 88387787777,328404398513,1220184956261,4533591310674,16844536614515

%N Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

%C Column 2 of A318068.

%H R. H. Hardin, <a href="/A318062/b318062.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) +3*a(n-2) -a(n-3) -a(n-4)

%e Some solutions for n=5

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

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

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

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

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

%Y Cf. A318068.

%K nonn

%O 1,2

%A _R. H. Hardin_, Aug 15 2018