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A295209 Number of n X 4 0..1 arrays with each 1 horizontally or vertically adjacent to 2 or 3 1's.

%I A295209 #6 Jun 22 2022 11:22:27
%S A295209 1,7,27,147,916,4938,27208,152236,848992,4746938,26555583,148468255,
%T A295209 830063597,4640855585,25946470239,145065530889,811058197498,
%U A295209 4534601269690,25352811924120,141746752099136,792501412285360
%N A295209 Number of n X 4 0..1 arrays with each 1 horizontally or vertically adjacent to 2 or 3 1's.
%C A295209 Column 4 of A295213.
%H A295209 R. H. Hardin, <a href="/A295209/b295209.txt">Table of n, a(n) for n = 1..210</a>
%F A295209 Empirical: a(n) = 8*a(n-1) -17*a(n-2) +27*a(n-3) -66*a(n-4) +182*a(n-5) -188*a(n-6) -199*a(n-7) -22*a(n-8) +185*a(n-9) +385*a(n-10) +169*a(n-11) +49*a(n-12) +408*a(n-13) +516*a(n-14) -492*a(n-15) -1779*a(n-16) -408*a(n-17) +326*a(n-18) -331*a(n-19) +505*a(n-20) -310*a(n-21) +217*a(n-22) -111*a(n-23) +4*a(n-24) -16*a(n-25) +4*a(n-26) +4*a(n-27) -a(n-28).
%e A295209 Some solutions for n=7
%e A295209 ..0..0..1..1. .1..1..1..1. .1..1..1..1. .1..1..0..0. .0..1..1..1
%e A295209 ..0..0..1..1. .1..0..1..1. .1..0..1..1. .1..1..1..0. .1..1..1..1
%e A295209 ..0..0..1..1. .1..1..1..1. .1..1..0..0. .1..0..1..0. .1..0..0..0
%e A295209 ..0..0..1..1. .0..1..0..0. .0..1..1..0. .1..0..1..0. .1..1..1..0
%e A295209 ..1..1..1..1. .0..1..1..0. .0..0..1..0. .1..0..1..0. .1..1..1..0
%e A295209 ..1..1..0..1. .0..1..1..0. .0..1..1..0. .1..1..1..0. .0..0..1..1
%e A295209 ..0..1..1..1. .0..0..0..0. .0..1..1..0. .1..1..0..0. .0..0..1..1
%Y A295209 Cf. A295213.
%K A295209 nonn
%O A295209 1,2
%A A295209 _R. H. Hardin_, Nov 17 2017