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A217450 Number of n X 1 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 1 array.

%I A217450 #9 Feb 19 2018 08:54:07
%S A217450 3,3,9,17,37,77,163,343,723,1523,3209,6761,14245,30013,63235,133231,
%T A217450 280707,591427,1246089,2625409,5531525,11654477,24555043,51735495,
%U A217450 109002515,229659507,483874057,1019483609,2147969733,4525598973
%N A217450 Number of n X 1 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 1 array.
%C A217450 Column 1 of A217457.
%H A217450 R. H. Hardin, <a href="/A217450/b217450.txt">Table of n, a(n) for n = 1..210</a>
%F A217450 Empirical: a(n) = 2*a(n-1) + a(n-4).
%F A217450 Empirical g.f.: x*(3 - 3*x + 3*x^2 - x^3) / (1 - 2*x - x^4). - _Colin Barker_, Feb 19 2018
%e A217450 All solutions for n=3:
%e A217450 ..1....2....0....2....1....2....0....1....0
%e A217450 ..0....0....0....2....1....1....0....1....0
%e A217450 ..0....0....2....2....1....1....1....2....0
%K A217450 nonn
%O A217450 1,1
%A A217450 _R. H. Hardin_, Oct 03 2012