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 A217375 #12 Jun 24 2019 20:16:24 %S A217375 0,0,0,0,0,0,0,0,0,8,40,168,604,2076,7320,26132,93352,333992,1199716, %T A217375 4329180 %N A217375 Number of trivially compound perfect squared rectangles of order n up to symmetries of the rectangle. %C A217375 A squared rectangle is a rectangle dissected into a finite number, two or more, of squares. If no two of these squares have the same size the squared rectangle is perfect. The order of a squared rectangle is the number of constituent squares. %C A217375 A squared rectangle is simple if it does not contain a smaller squared rectangle, compound if it does, and trivially compound if a constituent square has the same side length as a side of the squared rectangle under consideration. %H A217375 I. Gambini, <a href="http://alain.colmerauer.free.fr/alcol/ArchivesPublications/Gambini/carres.pdf">Quant aux carrés carrelés</a>, Thesis, Université de la Méditerranée Aix-Marseille II, 1999, p. 24. [A217153 up to a(18).] %H A217375 <a href="/index/Sq#squared_rectangles">Index entries for squared rectangles</a> %F A217375 a(n) >= 2*a(n-1) + 4*A002839(n-1) + 4*A217153(n-1), with equality for n<19. %Y A217375 Cf. A217374 (counts symmetries of squared subrectangles as equivalent). %Y A217375 Cf. A217154. %K A217375 nonn,hard,more %O A217375 1,10 %A A217375 _Geoffrey H. Morley_, Oct 02 2012 %E A217375 a(20) corrected by _Geoffrey H. Morley_, Oct 12 2012