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 A123849 #21 Oct 08 2017 05:18:00 %S A123849 1,1,1,11,21,31,41 %N A123849 Number of ways to build a contiguous building with n LEGO blocks of size 5 X 5 on top of a fixed block of the same size so that the building is symmetric after a rotation by 90 degrees. %C A123849 The base block is not counted among the n and must be the only block in the bottom layer of the building. %H A123849 M. Abrahamsen and S. Eilers, <a href="http://dx.doi.org/10.1080/10586458.2011.564539">On the asymptotic enumeration of LEGO structures</a>, Exper Math. 20 (2) (2011) 145-152. %H A123849 B. Durhuus and S. Eilers, <a href="http://arxiv.org/abs/math/0504039">On the entropy of LEGO</a>, arXiv:math/0504039 [math.CO], 2005. %H A123849 B. Durhuus and S. Eilers, <a href="http://link.springer.com/article/10.1007/s12190-013-0730-9">On the entropy of LEGO</a>, J. Appl. Math. Comput. 45 (1-2) (2014), 433-448. %H A123849 S. Eilers, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.123.5.415">The LEGO counting problem</a>, Amer. Math. Monthly, 123 (May 2016), 415-426. %K A123849 nonn,more %O A123849 1,4 %A A123849 _Søren Eilers_, Oct 29 2006