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 A068923 #10 Oct 17 2019 11:44:28 %S A068923 1,4,4,2,3,3,3,5,5,6,8,8,11,13,14,19,21,25,32,35,44,53,60,76,88,104, %T A068923 129,148,180,217,252,309,365,432,526,617,741,891,1049,1267,1508,1790, %U A068923 2158,2557,3057,3666,4347,5215,6223,7404,8881,10570,12619,15104,17974 %N A068923 Number of ways to tile a 4 X n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point. %H A068923 R. J. Mathar, <a href="http://arxiv.org/abs/1311.6135">Paving rectangular regions with rectangular tiles,....</a>, arXiv:1311.6135 [math.CO], Table 3. %H A068923 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1,0,1). %F A068923 For n >= 9, a(n) = a(n-3) + a(n-5). %F A068923 G.f.: x*(x+1)*(2*x^6+x^5+x^4-x^2-3*x-1)/(-1+x^5+x^3) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 28 2009] %Y A068923 Cf. A068929 for incongruent tilings, A068920 for more info. First column of A272473. %K A068923 easy,nonn %O A068923 1,2 %A A068923 _Dean Hickerson_, Mar 11 2002 %E A068923 G.f. proposed by Maksym Voznyy checked and corrected by _R. J. Mathar_, Sep 16 2009.