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 A271509 #16 Apr 09 2016 15:51:46 %S A271509 5,5,5,5,2,13,13,13,13,14,17,17,17,17,14,25,25,25,25,34,29,29,29,29,2, %T A271509 37,37,37,37,46,41,41,41,41,62,53,53,53,53,34,61,61,61,61,98,65,65,65, %U A271509 65,94,65,65,65,65,46,73,73,73,73,14 %N A271509 List of 5-tuples: primitive integral pentagon sides in Cairo tiling. %C A271509 Refer to Cairo tiling by Stick Cross Method (see details in the links). Each pentagon has four sides of equal length and one side which is either shorter or longer. All sides can be taken to have integral lengths related to primitive Pythagorean triples A103606. %C A271509 If Pythagorean triple = (a, b, c), the 5-tuple is (s1, s2, s3, s4, s5) with s1 = s2 = s3 = s4 = c and s5 = 2*(b-a). See illustration in the links. %H A271509 David Bailey's World of Escher-like Tessellations, <a href="http://www.tess-elation.co.uk/cairo-tiling/study-1">Stick Cross Method</a> %H A271509 Kival Ngaokrajang, <a href="/A271509/a271509.pdf">Illustration of initial terms</a>, <a href="/A271509/a271509_1.pdf">Excel calculation sheet</a> %H A271509 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cairo_pentagonal_tiling">Cairo pentagonal tiling</a> %e A271509 List begins: %e A271509 5, 5, 5, 5, 2, %e A271509 13, 13, 13, 13, 14, %e A271509 17, 17, 17, 17, 14, %e A271509 25, 25, 25, 25, 34, %e A271509 29, 29, 29, 29, 2, %e A271509 ... %Y A271509 Cf. A103606. %K A271509 nonn,tabf %O A271509 1,1 %A A271509 _Kival Ngaokrajang_, Apr 09 2016