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 A210020 #8 Jun 10 2016 00:21:00 %S A210020 247053168,264057138,264075138,264138057,264138075,426057138, %T A210020 426075138,426138057,426138075,531680247,531680742,532407168, %U A210020 532416807,570264138,570426138,571380264,571380426,705324168,708423516,716084235,716805324,742053168,750264138,750426138,751380264,751380426,842071635,842350716,842351607 %N A210020 In base 9, numbers n which have 9 distinct digits, do not start with 0, and have property that the product (written in base 9) of any two adjacent digits is a substring of n. %C A210020 Computed by Jean-Paul Davalan. %C A210020 The analog in base 2 is 10; in base 3, 102,120,201,210. %H A210020 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/DixChiffres.htm">10 different digits, 9 products</a> %H A210020 E. Angelini, <a href="/A198298/a198298.pdf">10 different digits, 9 products</a> [Cached copy, with permission] %Y A210020 A generalization of A198298. Cf. A210013-A210020, A203569, A203566. %K A210020 nonn,base,fini,full %O A210020 1,1 %A A210020 _N. J. A. Sloane_, Mar 16 2012