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A207909 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 0 1 1 vertically.

%I A207909 #7 Jul 22 2025 20:58:40
%S A207909 9,81,261,841,4089,19881,80511,326041,1428071,6255001,26473085,
%T A207909 112042225,481310535,2067611841,8824602441,37663553041,161202941369,
%U A207909 689961148321,2949462033565,12608429197225,53927628353015,230654354661481
%N A207909 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 0 1 1 vertically.
%C A207909 Row 4 of A207908
%H A207909 R. H. Hardin, <a href="/A207909/b207909.txt">Table of n, a(n) for n = 1..210</a>
%F A207909 Empirical: a(n) = 3*a(n-1) +15*a(n-3) +67*a(n-4) -103*a(n-5) -69*a(n-6) -157*a(n-7) -735*a(n-8) +867*a(n-9) +665*a(n-10) +273*a(n-11) +2309*a(n-12) -2157*a(n-13) -1104*a(n-14) -82*a(n-15) -2401*a(n-16) +1858*a(n-17) +342*a(n-18) +28*a(n-19) +644*a(n-20) -456*a(n-21) -32*a(n-22) -48*a(n-24) +32*a(n-25)
%e A207909 Some solutions for n=4
%e A207909 ..1..0..1..1....0..0..1..1....1..1..1..1....1..1..0..1....1..1..1..0
%e A207909 ..0..0..1..1....1..0..0..1....1..1..0..1....1..0..1..1....1..0..1..1
%e A207909 ..0..1..1..1....0..1..1..1....0..1..1..1....1..0..0..1....0..1..1..0
%e A207909 ..1..0..0..1....1..0..0..1....1..0..0..1....0..1..1..1....0..0..1..1
%K A207909 nonn
%O A207909 1,1
%A A207909 _R. H. Hardin_ Feb 21 2012