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

%I #7 Apr 19 2020 23:57:34

%S 1,1,5,23,113,576,2583,11656,54738,252959,1159927,5359097,24760544,

%T 114126327,526426848,2429504050,11207820807,51702119063,238537489057,

%U 1100501704736,5077031912807,23422773519432,108060889914594

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

%C Diagonal of A299595.

%H R. H. Hardin, <a href="/A299589/b299589.txt">Table of n, a(n) for n = 1..70</a>

%F Empirical: a(n) = 3*a(n-1) +2*a(n-2) +28*a(n-3) -2*a(n-4) -42*a(n-5) -56*a(n-6) +50*a(n-7) -44*a(n-8) +30*a(n-9) -44*a(n-10) +2*a(n-11) +2*a(n-12) -a(n-14) +a(n-15) for n>18.

%e Some solutions for n=5

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

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

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

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

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

%Y Cf. A299595.

%K nonn

%O 1,3

%A _R. H. Hardin_, Feb 13 2018