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 A029495 #28 Jun 10 2025 19:06:09
%S A029495 1,5,337
%N A029495 Numbers k such that k divides the (right) concatenation of all numbers <= k written in base 2 (most significant digit on right).
%C A029495 This sequence differs from A061931 in that all least significant zeros are kept during concatenation.
%C A029495 No more terms < 10^7. - _Lars Blomberg_, Oct 01 2011
%H A029495 <a href="/index/N#concat">Index entries for related sequences</a>
%e A029495 12345 -> (1)(01)(11)(001)(101) base 2 -> 10111001101 base 2 = 1485 and 5 divides 1485.
%t A029495 b = 2; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[c, Reverse[IntegerDigits[#, b]]], b], #] &] (* _Robert Price_, Mar 12 2020 *)
%o A029495 (PARI) is(n) = my(t=[]); for(k=1, n, t=concat(t, Vecrev(binary(k)))); if(Mod(subst(Pol(t), x, 2), n)==0, return(1), return(0)) \\ _Felix Fröhlich_, Jul 06 2017
%Y A029495 Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.
%K A029495 nonn,base,bref,more
%O A029495 1,2
%A A029495 _Olivier Gérard_
%E A029495 Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002
%E A029495 Additional comments, more terms and example from Larry Reeves (larryr(AT)acm.org), May 25 2001