cp's OEIS Frontend

A208687 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 1 and 1 0 1 vertically.

%I A208687 #7 Jul 22 2025 21:27:48
%S A208687 42,1764,7086,40581,269766,1346961,6398617,31733422,152209092,
%T A208687 711191700,3333256899,15574230936,72263776797,334784881455,
%U A208687 1550207903794,7167239737000,33109416636066,152910959100921,705957016908150
%N A208687 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 1 and 1 0 1 vertically.
%C A208687 Column 7 of A208688
%H A208687 R. H. Hardin, <a href="/A208687/b208687.txt">Table of n, a(n) for n = 1..210</a>
%F A208687 Empirical: a(n) = 6*a(n-1) -7*a(n-2) +31*a(n-3) -128*a(n-4) -30*a(n-5) -116*a(n-6) +788*a(n-7) +798*a(n-8) +678*a(n-9) -2778*a(n-10) -1872*a(n-11) -1842*a(n-12) +3336*a(n-13) +1554*a(n-14) +378*a(n-15) -2736*a(n-16) +912*a(n-17) +312*a(n-18) +1590*a(n-19) -540*a(n-20) -228*a(n-21) -222*a(n-22) +210*a(n-23) -86*a(n-24) +24*a(n-25) -38*a(n-26) +8*a(n-27) -a(n-28) -a(n-30) +a(n-31)
%e A208687 Some solutions for n=4
%e A208687 ..0..1..1..1..0..1..0....1..1..0..1..0..1..1....1..1..0..1..0..1..1
%e A208687 ..1..1..1..1..1..1..0....1..1..0..1..0..1..1....0..1..0..1..0..1..1
%e A208687 ..0..1..1..1..0..1..1....0..1..0..1..0..1..1....0..1..0..1..0..1..1
%e A208687 ..0..1..0..1..0..1..0....0..1..1..0..1..0..1....1..0..1..0..1..1..1
%K A208687 nonn
%O A208687 1,1
%A A208687 _R. H. Hardin_ Mar 01 2012