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Number of 3 X n 0..1 arrays with every element equal to 0, 1, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1

%I #6 Jan 16 2022 01:12:11

%S 4,4,11,15,21,52,118,220,408,852,1764,3460,6796,13732,27708,55140,

%T 109788,220132,441244,881380,1760796,3523812,7051548,14098660,

%U 28189468,56387812,112791324,225564900,451098396,902232292,1804527388,3608983780

%N Number of 3 X n 0..1 arrays with every element equal to 0, 1, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

%C Row 3 of A302515.

%H R. H. Hardin, <a href="/A302516/b302516.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +2*a(n-3) +4*a(n-4) for n>7.

%e Some solutions for n=5

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

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

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

%Y Cf. A302515.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 09 2018