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A183340 Number of nX8 binary arrays with each 1 adjacent to exactly one 1 vertically and one 1 horizontally.

%I A183340 #7 Jul 22 2025 08:50:00
%S A183340 1,19,63,193,1005,4133,16029,68662,286079,1170324,4869491,20218182,
%T A183340 83588667,346493199,1436419555,5949727953,24653341080,102162618558,
%U A183340 423291469427,1753914307948,7267558737304,30113168208503,124774750283399
%N A183340 Number of nX8 binary arrays with each 1 adjacent to exactly one 1 vertically and one 1 horizontally.
%C A183340 Equivalent to all 1s connected only in 2X2 blocks
%C A183340 Column 8 of A183342
%H A183340 R. H. Hardin, <a href="/A183340/b183340.txt">Table of n, a(n) for n = 1..200</a>
%F A183340 Empirical: a(n)=a(n-1)+4*a(n-2)+33*a(n-3)+40*a(n-4)-27*a(n-5)-190*a(n-6)-384*a(n-7)+149*a(n-8)+768*a(n-9)+398*a(n-10)-281*a(n-11)+312*a(n-12)-879*a(n-13)-1871*a(n-14)+351*a(n-15)+2551*a(n-16)-928*a(n-17)+499*a(n-18)+267*a(n-19)-947*a(n-20)-295*a(n-21)-55*a(n-22)+284*a(n-23)+192*a(n-24)+136*a(n-25)+98*a(n-26)-86*a(n-27)+17*a(n-28)-4*a(n-29)-19*a(n-30)+3*a(n-31)-12*a(n-32)
%e A183340 Some solutions for 5X8
%e A183340 ..0..1..1..0..0..1..1..0....1..1..0..0..0..0..0..0....1..1..0..0..0..0..0..0
%e A183340 ..0..1..1..0..0..1..1..0....1..1..0..1..1..0..0..0....1..1..0..0..0..0..0..0
%e A183340 ..0..0..0..0..0..0..0..0....0..0..0..1..1..0..0..0....0..0..0..0..0..0..0..0
%e A183340 ..0..1..1..0..0..0..1..1....1..1..0..0..0..1..1..0....1..1..0..0..1..1..0..0
%e A183340 ..0..1..1..0..0..0..1..1....1..1..0..0..0..1..1..0....1..1..0..0..1..1..0..0
%K A183340 nonn
%O A183340 1,2
%A A183340 _R. H. Hardin_ Jan 04 2011