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 A088702 #12 Oct 06 2019 18:21:30 %S A088702 0,1,2,7,28,124,588,2939,15292,82168,453376,2558074,14712038,86029132, %T A088702 510455002,3068304865,18658787150,114663168405,711391109162, %U A088702 4452321247688,28090360338572,178550339417087,1142799275636690 %N A088702 Number of polygons with polygonal holes on the square lattice enumerated by half-perimeter. %C A088702 The polygons and the hole are self-avoiding and mutually-avoiding, i.e., no degree four vertices are allowed. Translations are allowed, rotations and reflections are not allowed. The contribution of the holes to the perimeter is counted. The number of the holes is not limited, possibly no holes. %D A088702 A. J. Guttmann, I. Jensen, L. H. Wong and I. G. Enting, J. Phys. A, Vol. 33 (2000) 1735-1764. %H A088702 I. Jensen, <a href="/A088702/b088702.txt">Table of n, a(n) for n = 1..43</a> (from link below) %H A088702 I. Jensen, <a href="https://researchers.ms.unimelb.edu.au/~ij@unimelb/polygons/series/square.perim.allholes.ser">More terms</a> %H A088702 I. Jensen, <a href="https://researchers.ms.unimelb.edu.au/~ij@unimelb/polygons/Polygons_ser.html">Series expansions for self-avoiding polygons</a> %Y A088702 Cf. A002931 (self-avoiding polygons), A056634 (self-avoiding polygons with exactly one hole), A056638 (self-avoiding polygons with exactly two holes), A056639 (self-avoiding polygons with exactly three holes). %K A088702 nonn %O A088702 1,3 %A A088702 Markus Voege (markus.voege(AT)inria.fr), Nov 23 2003