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 A061972 #13 Mar 09 2020 22:00:12
%S A061972 1,3,9,27,33,36,81,183,223,261,263,351,585,1035,1092,1173,1732,2235,
%T A061972 2628,3492,8577,11592,13617,15663,20664,20709,23333,25848,52689,67608,
%U A061972 334536,837112,2765341,5319444
%N A061972 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 19 (most significant digit on right).
%C A061972 This sequence differs from A029536 in that all least significant zeros are kept during concatenation.
%C A061972 No more terms < 7*10^6.
%H A061972 <a href="/index/N#concat">Index entries for related sequences</a>
%e A061972 See A061955 for example.
%t A061972 b = 19; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[Reverse[IntegerDigits[#, b]], c], b], #] &] (* _Robert Price_, Mar 09 2020 *)
%Y A061972 Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.
%K A061972 nonn,base,more
%O A061972 1,2
%A A061972 Larry Reeves (larryr(AT)acm.org), May 24 2001
%E A061972 Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002
%E A061972 a(32)-a(34) from _Lars Blomberg_, Jul 31 2011