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A280550 Number of n X 4 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%I A280550 #7 Feb 13 2019 11:33:49
%S A280550 1,34,144,382,832,1666,3182,5886,10680,19122,33920,59754,104690,
%T A280550 182598,317264,549398,948528,1633186,2805094,4807006,8220440,14030634,
%U A280550 23904656,40659818,69051850,117099910,198312144,335420782,566645728,956190466
%N A280550 Number of n X 4 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
%H A280550 R. H. Hardin, <a href="/A280550/b280550.txt">Table of n, a(n) for n = 1..210</a>
%F A280550 Empirical: a(n) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 12*a(n-4) - 12*a(n-5) - 3*a(n-6) + 6*a(n-7) - a(n-9) for n>11.
%F A280550 Empirical g.f.: x*(1 + 28*x - 48*x^2 - 79*x^3 + 86*x^4 + 142*x^5 - 57*x^6 - 134*x^7 + 46*x^8 + 39*x^9 - 36*x^10) / ((1 - x)^3*(1 - x - x^2)^3). - _Colin Barker_, Feb 13 2019
%e A280550 Some solutions for n=4:
%e A280550 ..0..1..0..1. .0..1..0..1. .0..1..0..0. .0..1..1..0. .0..1..0..1
%e A280550 ..0..0..1..0. .1..0..1..1. .1..0..1..0. .1..0..0..1. .1..0..1..1
%e A280550 ..1..1..0..1. .0..1..0..1. .0..1..0..1. .1..0..1..1. .1..1..0..1
%e A280550 ..0..1..0..1. .0..1..0..1. .1..0..1..1. .0..1..0..1. .0..0..1..0
%Y A280550 Column 4 of A280554.
%K A280550 nonn
%O A280550 1,2
%A A280550 _R. H. Hardin_, Jan 05 2017