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%I #4 Mar 31 2018 15:45:41
%S 4,32,148,748,3657,18108,89658,444359,2202106,10912859,54080195,
%T 268002332,1328125172,6581720890,32616691234,161636836900,
%U 801015249307,3969549529089,19671689743540,97485967746453,483106130247259
%N Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
%C Row 3 of A302069.
%H R. H. Hardin, <a href="/A302070/b302070.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) +4*a(n-2) +2*a(n-3) +7*a(n-4) +7*a(n-5) -4*a(n-6) -10*a(n-7) -3*a(n-8) -5*a(n-9) -11*a(n-10) +2*a(n-11) +8*a(n-12) +a(n-13) -a(n-15) for n>18
%e Some solutions for n=5
%e ..0..1..0..1..1. .0..0..1..0..1. .0..1..1..0..1. .0..1..0..0..0
%e ..1..0..0..1..1. .1..0..0..1..1. .0..1..0..1..0. .0..1..1..1..1
%e ..1..1..0..0..1. .0..1..0..0..0. .0..1..0..0..1. .1..0..0..0..0
%Y Cf. A302069.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 31 2018