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 A261373 #10 Dec 30 2018 15:22:17 %S A261373 36,39,60,97,154,247,392,618,977,1548,2461,3894,6176,9774,15513,24552, %T A261373 38963,61662,97854,154866,245769,388956,617257,976878,1550272,2453478, %U A261373 3893581,6162024,9778911,15476214,24560198,38869242,61684093,97621932 %N A261373 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00001011 00010101 or 01010101. %H A261373 R. H. Hardin, <a href="/A261373/b261373.txt">Table of n, a(n) for n = 1..210</a> %F A261373 Empirical: a(n) = a(n-2) + 3*a(n-4) + 2*a(n-6) for n>12. %F A261373 Empirical g.f.: x*(36 + 39*x + 24*x^2 + 58*x^3 - 14*x^4 + 33*x^5 - 14*x^6 + 2*x^7 + 3*x^8 - 5*x^9 - 2*x^11) / (1 - x^2 - 3*x^4 - 2*x^6). - _Colin Barker_, Dec 30 2018 %e A261373 Some solutions for n=4: %e A261373 0 1 0 1 0 0 1 0 1 1 0 0 0 1 0 1 0 1 1 0 1 %e A261373 1 0 0 1 0 0 0 0 1 0 1 0 1 0 1 0 0 1 0 1 0 %e A261373 0 1 0 0 1 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 1 %e A261373 1 0 1 1 0 1 0 1 1 0 1 0 1 0 1 1 0 1 0 1 0 %e A261373 0 1 0 0 1 0 1 1 0 1 0 0 0 0 0 0 1 0 1 0 1 %e A261373 0 0 1 1 0 1 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 %Y A261373 Column 1 of A261380. %K A261373 nonn %O A261373 1,1 %A A261373 _R. H. Hardin_, Aug 17 2015