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%I #9 Jun 19 2018 12:35:30
%S 80,56,157,110,311,218,619,434,1235,866,2468,1730,4934,3458,9866,6914,
%T 19730,13826,39458,27650,78914,55298,157826,110594,315650,221186,
%U 631298,442370,1262594,884738,2525186,1769474,5050370,3538946,10100738,7077890
%N Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor.
%C Column 3 of A207149.
%H R. H. Hardin, <a href="/A207144/b207144.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) for n>10.
%F Empirical g.f.: x*(80 - 24*x - 59*x^2 + x^3 - x^4 + x^5 - x^6 + x^7 - x^8 + x^9) / ((1 - x)*(1 - 2*x^2)). - _Colin Barker_, Jun 19 2018
%e Some solutions for n=4:
%e ..2..2..0..1....1..0..1..0....0..1..0..1....0..1..0..2....0..1..0..1
%e ..1..0..2..0....0..1..0..1....2..0..1..0....2..0..1..0....1..0..1..0
%e ..0..1..0..2....1..0..1..0....0..2..0..1....0..2..0..1....0..1..0..1
%e ..1..0..1..0....0..1..0..1....2..0..2..0....1..0..2..0....1..0..1..0
%e ..0..1..0..1....2..0..1..0....0..2..0..2....0..1..0..2....0..1..0..1
%Y Cf. A207149.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 15 2012
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