A029514 - OEIS

A029514

Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 21 (most significant digit on right).

%I #21 Jan 14 2025 11:18:20

%S 1,3,5,7,15,25,55,80,143,187,192,387,1385,1760,4080,9040,9245,15565,

%T 17776,20080,28400,30019,30063,37312,38368,52217,56277,84480,97504,

%U 123040,293045,458560,1258528,2437600,2442000,3122240,7216880

%N Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 21 (most significant digit on right).

%C This sequence differs from A061950 in that all least significant zeros are kept during concatenation.

%C No more terms < 10^7. [_Lars Blomberg_, Oct 11 2011]

%H <a href="/index/N#concat">Index entries for related sequences</a>

%e See A029495 for example.

%t b = 21; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[c, Reverse[IntegerDigits[#, b]]], b], #] &] (* _Robert Price_, Mar 13 2020 *)

%Y Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.

%K nonn,base,more

%O 1,2

%A _Olivier Gérard_

%E Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002

%E Additional comments and more terms from Larry Reeves (larryr(AT)acm.org), May 25 2001

%E a(32)-a(37) from _Lars Blomberg_, Oct 11 2011