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 A261372 #5 Aug 17 2015 08:27:17 %S A261372 36,41,202,1040,5633,42302,461576,5441268,87288274,1757770516, %T A261372 47269754142,1497418790742,65202132975489,3410709440318090, %U A261372 240487233522340499,20318813275802198468,2337266627779577763890 %N A261372 Number of (n+2)X(n+2) 0..1 arrays with each 3X3 subblock having clockwise perimeter pattern 00001011 00010101 or 01010101. %C A261372 Diagonal of A261380. %H A261372 R. H. Hardin, <a href="/A261372/b261372.txt">Table of n, a(n) for n = 1..23</a> %e A261372 Some solutions for n=4 %e A261372 ..1..0..1..0..0..0....1..0..0..1..0..1....0..0..0..1..0..1....1..0..1..0..1..0 %e A261372 ..0..1..0..1..0..1....1..0..0..0..1..0....1..0..1..0..1..0....0..1..0..1..0..0 %e A261372 ..0..0..1..0..1..0....0..1..0..1..0..0....0..1..0..1..0..1....1..0..1..0..1..0 %e A261372 ..0..1..0..1..0..1....1..0..1..0..1..0....1..0..1..0..1..0....0..0..0..1..0..1 %e A261372 ..1..0..1..0..0..0....0..1..0..1..0..1....0..0..0..1..0..1....1..0..1..0..0..0 %e A261372 ..0..0..0..1..0..0....0..0..1..0..1..0....0..0..1..0..0..0....0..1..0..1..0..0 %Y A261372 Cf. A261380. %K A261372 nonn %O A261372 1,1 %A A261372 _R. H. Hardin_, Aug 17 2015