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 A278691 #17 Aug 15 2017 13:52:51 %S A278691 1,1,1,2,4,9,22,60,176,565,1980,7528,30843,135248,630004,3097780, %T A278691 15991395,86267557,484446620,2822677523,17017165987 %N A278691 Number of graded lattices on n nodes. %C A278691 A finite lattice is graded if, for any element, all paths from the bottom to that element have the same length. %H A278691 J. Heitzig and J. Reinhold, <a href="http://dx.doi.org/10.1007/PL00013837">Counting finite lattices</a>, Algebra Universalis, 48 (2002), 43-53. %H A278691 J. Kohonen, <a href="http://arxiv.org/abs/1708.03750">Generating modular lattices up to 30 elements</a>, arXiv:1708.03750 [math.CO] preprint (2017). %H A278691 M. Malandro, <a href="http://www.shsu.edu/mem037/Lattices.html">The unlabeled lattices on <=15 nodes</a>, (listing of lattices; graded lattices are a subset of these). %Y A278691 Cf. A006966 (lattices), A229202 (semimodular lattices). %K A278691 nonn,more %O A278691 1,4 %A A278691 _Jukka Kohonen_, Nov 26 2016 %E A278691 a(16)-a(21) from Kohonen (2017), by _Jukka Kohonen_, Aug 15 2017