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%I #7 Oct 20 2018 14:20:06
%S 81,414,2148,11064,57132,294648,1520856,7845624,40488216,208893336,
%T 1077925704,5561714424,28698381576,148076913912,764063601480,
%U 3942427621752,20342443076808,104963700280056,541598357861448
%N Number of (n+1) X (1+1) 0..2 arrays colored with the sets of distinct values in every 2 X 2 subblock.
%H R. H. Hardin, <a href="/A236148/b236148.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 18*a(n-2) + 16*a(n-3) + 12*a(n-4) - 12*a(n-5).
%F Empirical g.f.: 3*x*(27 + 111*x + 92*x^2 + 56*x^3 - 64*x^4) / (1 - x - 18*x^2 - 16*x^3 - 12*x^4 + 12*x^5). - _Colin Barker_, Oct 20 2018
%e Some solutions for n=5:
%e ..0..2....2..2....0..1....1..2....0..0....2..1....2..1....2..1....1..1....0..0
%e ..1..1....2..0....1..1....0..0....0..1....0..2....0..2....2..2....0..0....2..2
%e ..0..1....0..1....0..2....0..2....2..2....2..2....2..0....2..2....2..0....1..0
%e ..2..2....1..1....2..2....1..2....2..2....1..1....0..1....2..1....1..0....1..0
%e ..0..0....1..2....1..2....1..2....1..2....1..0....1..0....1..0....1..1....2..0
%e ..0..0....1..0....0..1....2..0....0..1....1..2....2..2....0..0....2..0....0..0
%Y Column 1 of A236155.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 19 2014
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