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 A121786 #16 Jan 10 2019 22:39:24 %S A121786 1,7,160,11408,2522191,1718769373,3598611604598,23098353998190640, %T A121786 453839082673896579243,27266319759961440667165921, %U A121786 5005013940387988257218110301496,2805250606288167736619664411164848668 %N A121786 "Cow patches" on the square lattice (see Jensen web site for further information). %H A121786 I. Jensen, <a href="/A121786/b121786.txt">Table of n, a(n) for n = 1..19</a> [from the Jensen link below] %H A121786 M. Bousquet-Mélou, A. J. Guttmann, Iwan Jensen, <a href="http://dx.doi.org/10.1088/0305-4470/38/42/001">Self-avoiding walks crossing a square</a>, J. Phys. A: Math. Gen. 38 (2005) 9159-9181, Table 2. %H A121786 I. Jensen, <a href="https://web.archive.org/web/20070612141707/http://www.ms.unimelb.edu.au/~iwan/saw/SAW_ser.html">Series Expansions for Self-Avoiding Walks</a>. %H A121786 I. Jensen, <a href="https://web.archive.org/web/20070613021812/http://www.ms.unimelb.edu.au/~iwan/saw/series/saw_cowpatch.ser">Cow patches</a>. %Y A121786 Cf. A007764, A121785. %K A121786 nonn %O A121786 1,2 %A A121786 _N. J. A. Sloane_, Aug 30 2006