This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A181240 #5 Jul 22 2025 08:38:23 %S A181240 32,634,13262,275690,5735478,119310334,2481942354,51630303190, %T A181240 1074033301458,22342450688162,464776188850718,9668451712623486, %U A181240 201126823551119586,4183916965585685474,87035437968274038914 %N A181240 Number of nX5 binary matrices with no 2X2 circuit having pattern 0101 in any orientation. %C A181240 Column 5 of A181245 %H A181240 R. H. Hardin, <a href="/A181240/b181240.txt">Table of n, a(n) for n=1..200</a> %F A181240 Empirical: a(n)=21*a(n-1)+9*a(n-2)-278*a(n-3)+73*a(n-4)+790*a(n-5)-662*a(n-6)+29*a(n-7)+69*a(n-8)-10*a(n-9) %K A181240 nonn %O A181240 1,1 %A A181240 _R. H. Hardin_ Oct 10 2010