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 A123818 #13 Sep 09 2017 03:31:38 %S A123818 1,3,31,412,6435,106108,1825803,32320892,584956651,10772558067, %T A123818 201219520632 %N A123818 Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 2 X 2. %H A123818 S. Eilers, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.123.5.415">The LEGO counting problem</a>, Amer. Math. Mnthly, 123 (May 2016), 415-426. %H A123818 <a href="/wiki/Index_to_OEIS:_Section_Lc#LEGO">Index entry for sequences related to LEGO blocks</a> %Y A123818 Cf. A112389, A123762-A123827, A123829-A123849. %K A123818 nonn,hard,more %O A123818 1,2 %A A123818 _Søren Eilers_, Oct 29 2006