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 A029506 #22 Jan 14 2025 11:09:50
%S A029506 1,3,9,15,21,25,35,47,48,87,240,320,672,896,1760,2592,2688,3659,5152,
%T A029506 15456,16800,53200,60288,75360,92605,92736,121600,189648,204176,
%U A029506 334827,382368,401472,443919,1070720,1836855,2010432,4384128,5566077
%N A029506 Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 13 (most significant digit on right).
%C A029506 This sequence differs from A061942 in that all least significant zeros are kept during concatenation.
%C A029506 No more terms < 10^7. - _Lars Blomberg_, Oct 07 2011
%H A029506 <a href="/index/N#concat">Index entries for related sequences</a>
%e A029506 See A029495 for example.
%t A029506 b = 13; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[c, Reverse[IntegerDigits[#, b]]], b], #] &] (* _Robert Price_, Mar 12 2020 *)
%o A029506 (PARI) lista(nn, m=13) = my(s, t); for(k=1, nn, s=k; while(s, t=t*m+s%m; s\=m); if(t%k==0, print1(k, ", "))); \\ _Jinyuan Wang_, Dec 05 2020
%Y A029506 Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.
%K A029506 nonn,base,more
%O A029506 1,2
%A A029506 _Olivier Gérard_
%E A029506 Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002
%E A029506 Additional comments and more terms from Larry Reeves (larryr(AT)acm.org), May 25 2001
%E A029506 a(33)-a(38) from _Lars Blomberg_, Oct 07 2011