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 A051657 #16 Aug 25 2020 06:05:54 %S A051657 1,30,38,39,52,67,68,99,119,120 %N A051657 Experimental values for number of equal circles that are packed into a square for which the density of the packing is strictly increasing. %D A051657 H. T. Croft, K. J. Falconer and R. K. Guy: Unsolved problems in geometry, Springer, New York, 1991. %H A051657 D. Boll, <a href="http://www.frii.com/~dboll/packing.html">Optimal Packing Of Circles And Spheres</a>. %H A051657 E. Friedman, <a href="https://erich-friedman.github.io/packing/index.html">Erich's Packing Center</a>. %H A051657 C. D. Maranas, C. A. Floudas and P. M. Pardalos, <a href="https://doi.org/10.1016/0012-365x(93)e0230-2">New results in the packing of equal circles in a square</a>, Discrete Mathematics 142 (1995), p. 287-293. %H A051657 K. J. Nurmela and Patric R. J. Östergård, <a href="http://www.inf.u-szeged.hu/~pszabo/Packing_circles.html">Packing up to 50 equal circles in a square</a>, Discrete Comput. Geom. 18 (1997) 1, p. 111-120. %H A051657 E. Specht, <a href="http://www.packomania.com/">www.packomania.com</a>. %K A051657 nonn %O A051657 1,2 %A A051657 Eckard Specht (eckard.specht(AT)physik.uni-magdeburg.de) %E A051657 I do not know how many of these values have been rigorously proved. - _N. J. A. Sloane_