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 A255540 #19 Apr 12 2015 17:34:41 %S A255540 1,1,2,6,15,51,173,681,2682 %N A255540 Number of connected digital images in Z^2 (regarding each point as connected to its 8 neighbors) on n points up to isomorphism. %C A255540 Also the number of polyplets (A030222) on n points up to isomorphism of adjacency graphs. %H A255540 P. C. Staecker, <a href="http://arxiv.org/abs/1502.06236">Some enumerations of binary digital images</a>, arXiv 1502.06236 [math.CO], 2015 (see table p. 6). %H A255540 P. C. Staecker, <a href="http://cstaecker.fairfield.edu/~cstaecker/files/research/enumerations/">Digital image enumerations</a> %e A255540 For n=4 the a(4)=6 images are: %e A255540 X X X X XX X X %e A255540 X X X X XX XX XX %e A255540 X X X X X %e A255540 X %Y A255540 Cf. A255539. %K A255540 nonn,hard,more %O A255540 1,3 %A A255540 _P. Christopher Staecker_, Feb 24 2015