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%I #7 Sep 25 2021 18:49:06
%S 9,81,217,611,1910,5132,13067,33937,86899,218763,551672,1390836,
%T 3491934,8760137,21976254,55062713,137841712,344913621,862466304,
%U 2155128256,5382374565,13435295369,33519373349,83589288631,208367881512
%N Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 1 1 and 1 0 1 vertically.
%C Column 4 of A207269.
%H R. H. Hardin, <a href="/A207265/b207265.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 7*a(n-1) -20*a(n-2) +48*a(n-3) -132*a(n-4) +259*a(n-5) -410*a(n-6) +790*a(n-7) -1191*a(n-8) +1369*a(n-9) -2166*a(n-10) +2658*a(n-11) -2175*a(n-12) +3264*a(n-13) -3430*a(n-14) +1780*a(n-15) -3185*a(n-16) +3012*a(n-17) -722*a(n-18) +2246*a(n-19) -1944*a(n-20) -13*a(n-21) -1068*a(n-22) +856*a(n-23) +180*a(n-24) +292*a(n-25) -248*a(n-26) -56*a(n-27) -48*a(n-28) +48*a(n-29) for n>31.
%e Some solutions for n=4
%e ..0..1..0..1....0..1..0..0....1..1..0..1....0..0..1..0....0..1..0..1
%e ..0..1..0..0....0..1..0..0....0..1..0..1....1..1..1..0....1..1..0..1
%e ..1..1..0..0....0..0..1..0....0..1..0..1....0..0..1..0....0..1..0..1
%e ..0..1..0..1....1..0..0..1....0..0..1..0....0..0..1..0....0..0..1..0
%Y Cf. A207269.
%K nonn
%O 1,1
%A _R. H. Hardin_ Feb 16 2012
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