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A029490 Numbers k that divide the (left) concatenation of all numbers <= k written in base 21 (most significant digit on left). 0

%I #20 Jul 04 2021 01:57:30

%S 1,5,25,43,55,128,275,1280,2816,5888,6400,12800,28160,33413,37376,

%T 129919,140800,286025,352000,990845,1050880,1773725,2848000,3581033,

%U 4343680,4428160,5624960,6732160,7553920,8497280,9249995,9872000,10938752,11426176,14558575,14569600,15368320,18998705,19312000,21362275,24208000,24934855,27632000,32432000,37022605,43193216,51382265,53717375,81016375

%N Numbers k that divide the (left) concatenation of all numbers <= k written in base 21 (most significant digit on left).

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

%t b = 21; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[IntegerDigits[#, b], c], b], #] &] (* _Robert Price_, Mar 12 2020 *)

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

%K nonn,base

%O 1,2

%A _Olivier GĂ©rard_

%E More terms from Andrew Gacek (andrew(AT)dgi.net), Feb 21 2000

%E More terms from Larry Reeves (larryr(AT)acm.org), May 24 2001

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

%E Thirty more terms from _Max Alekseyev_, May 15 2011

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Last modified May 10 05:27 EDT 2024. Contains 372356 sequences. (Running on oeis4.)