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%I #12 Mar 03 2018 13:57:19
%S 15,102,870,7566,68342,609086,5514982,49362414,446198614,4001326366,
%T 36118081094,324279012558,2924285830070,26275991783678,
%U 236797822738342,2128866218464686,19176856665755158,172465933376949982
%N Number of (n+1) X 2 0..3 arrays with the number of equal 2 X 2 subblock diagonal pairs and equal antidiagonal pairs differing from each horizontal or vertical neighbor, and new values 0..3 introduced in row major order.
%C Column 1 of A205431.
%H R. H. Hardin, <a href="/A205424/b205424.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 73*a(n-2) + 39*a(n-3) - 384*a(n-4) - 432*a(n-5) for n>6.
%F Empirical g.f.: x*(15 + 87*x - 327*x^2 - 1335*x^3 - 952*x^4 + 144*x^5) / ((1 - 9*x)*(1 - x - 4*x^2)*(1 + 9*x + 12*x^2)). - _Colin Barker_, Mar 03 2018
%e Some solutions for n=4:
%e 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 1
%e 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 1
%e 0 1 2 1 0 1 0 0 1 1 0 1 0 1 0 1 2 1 0 0
%e 0 1 0 2 1 0 1 1 1 1 2 1 2 3 1 0 1 2 0 0
%e 1 2 3 1 1 0 2 1 2 1 1 0 3 0 2 0 0 3 1 1
%Y Cf. A205431.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 27 2012