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Number of nX4 0..2 arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.
1

%I #4 Feb 13 2016 18:20:33

%S 60,290,1202,5848,28452,135912,640926,2990786,13835892,63544542,

%T 290056316,1317009868,5952527788,26795651036,120193389832,

%U 537427198324,2396207992178,10656560102448,47282655935580,209348341875062

%N Number of nX4 0..2 arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.

%C Column 4 of A268809.

%H R. H. Hardin, <a href="/A268805/b268805.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) +19*a(n-2) +10*a(n-3) -122*a(n-4) -320*a(n-5) -295*a(n-6) +8*a(n-7) +176*a(n-8) +20*a(n-9) -98*a(n-10) -6*a(n-11) +43*a(n-12) -6*a(n-13) -11*a(n-14) +6*a(n-15) -a(n-16) for n>19

%e Some solutions for n=4

%e ..2..2..2..2. .2..2..2..1. .1..2..1..2. .2..2..1..2. .0..2..2..2

%e ..2..1..2..1. .1..2..1..2. .1..2..2..2. .1..2..1..2. .1..2..1..2

%e ..1..2..2..2. .2..2..2..2. .2..2..2..1. .2..2..2..2. .2..2..2..2

%e ..2..2..1..2. .1..2..2..1. .1..2..2..2. .1..2..1..2. .1..2..2..2

%Y Cf. A268809.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 13 2016