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 A051020 #39 Feb 16 2025 08:32:41
%S A051020 1053274689,1089467253,1253094867,1267085493,1268547309,1269085473,
%T A051020 1273085469,1308547269,1308549267,1326854907,1327068549,1328746905,
%U A051020 1450687329,1450732869,1450867293,1450928673,1452687309,1452690873
%N A051020 Numbers that are 4-persistent but not 5-persistent.
%C A051020 A number n is k-persistent iff all of {n, 2*n, ..., k*n} are pandigital (in the sense of A171102).
%H A051020 Hans Havermann, <a href="/A051020/b051020.txt">Table of n, a(n) for n = 1..1000</a> (corrected by Sean A. Irvine, Apr 28 2022)
%H A051020 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PersistentNumber.html">Persistent Number</a>
%o A051020 (PARI) is_A051020(n)=for(i=1, 5, 9<#Set(Vec(Str(i*n))) || return(i>4)) \\ _M. F. Hasler_, Jan 10 2012
%Y A051020 Cf. A171102 (pandigital), A204047 (smallest n-persistent), A051264 (1-persistent), A051018 (2-persistent), A051019 (3-persistent), A204096 (5-persistent), A204097 (6-persistent).
%K A051020 nonn,base
%O A051020 1,1
%A A051020 _Eric W. Weisstein_
%E A051020 Definition corrected by Franklin T. Adams-Watters, Jan 09 2012
%E A051020 Sequence corrected by _Hans Havermann_, Jan 11 2012