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%I #7 Jun 09 2023 22:18:05
%S 0,1,15,314,3764,37557,353608,3178404,27582216,233397609,1936592863,
%T 15815427428,127479709618,1016314018380,8026733559938,62881710177968,
%U 489133088311108,3781016346686269,29064881546033136,222309716942266766
%N Number of n X 3 0..1 arrays with no 1 equal to more than three of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly two elements.
%C Column 3 of A284075.
%H R. H. Hardin, <a href="/A284070/b284070.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 21*a(n-1) -153*a(n-2) +484*a(n-3) -1254*a(n-4) +5199*a(n-5) -10697*a(n-6) +19671*a(n-7) -61194*a(n-8) +93379*a(n-9) -140298*a(n-10) +354402*a(n-11) -436616*a(n-12) +546228*a(n-13) -1123992*a(n-14) +1218808*a(n-15) -1193856*a(n-16) +1907040*a(n-17) -2009856*a(n-18) +1446528*a(n-19) -1456128*a(n-20) +1486336*a(n-21) -890880*a(n-22) +270336*a(n-23) -32768*a(n-24).
%e Some solutions for n=4
%e ..1..1..1. .1..0..0. .0..0..1. .1..0..0. .0..1..0. .1..1..0. .0..0..1
%e ..1..1..1. .0..1..0. .1..1..1. .0..1..1. .1..1..1. .1..0..0. .1..1..1
%e ..0..0..0. .1..1..1. .1..1..1. .1..1..1. .1..1..1. .1..1..1. .1..1..1
%e ..0..0..1. .1..1..1. .0..1..0. .0..1..1. .0..1..1. .1..1..1. .1..0..0
%Y Cf. A284075.
%K nonn
%O 1,3
%A _R. H. Hardin_, Mar 19 2017
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