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 A029519 #44 Jan 13 2025 13:18:42
%S A029519 1,3,7,17,27,63,92883,1556671
%N A029519 Numbers k such that k divides the (left) concatenation of all numbers <= k written in base 2 (most significant digit on right and removing all least significant zeros before concatenation).
%C A029519 This sequence differs from A061955 in that all least significant zeros are removed before concatenation.
%C A029519 No more terms < 10^7. - _Lars Blomberg_, Aug 31 2011
%H A029519 <a href="/index/N#concat">Index entries for related sequences</a>
%e A029519 7 is in the sequence as the left concatenation of numbers <= 7 is 7654321 which gives 7654321 -> (111)(011)(101)(001)(11)(01)(1) base 2 -> 1111110111111_2 = 8127, and 7 divides 8127.
%t A029519 b = 2; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[IntegerDigits[IntegerReverse[#, b], b], c], b], #] &] (* _Robert Price_, Mar 13 2020 *)
%o A029519 (J) mkcat =: 13 : 'y +. #. ; #:&.> |.&.#:&.> |. >:i. y'
%o A029519 (#~ (= mkcat"0)) >:i. 100x NB. _Stephen Makdisi_, May 03 2018
%Y A029519 Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.
%K A029519 nonn,base,more
%O A029519 1,2
%A A029519 _Olivier Gérard_
%E A029519 Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002
%E A029519 Additional comments and example from Larry Reeves (larryr(AT)acm.org), May 25 2001
%E A029519 Terms verified by _Rick L. Shepherd_, Feb 24 2009
%E A029519 1 more term from _Sean A. Irvine_, Oct 04 2009