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A029503 Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 10 (most significant digit on right). 2

%I #24 Mar 12 2020 21:53:20

%S 1,2,3,5,6,9,101,107,153,167,277,414,486,858,1659,2894,3093,4299,4842,

%T 8838,22734,31869,69492,361057,429786,462018,859002,1170801,1334667,

%U 1663923,6143512,6162396,6212646,7034661,8164443

%N Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 10 (most significant digit on right).

%C This sequence differs from A061939 in that all least significant zeros are kept during concatenation.

%C Right concatenation, reverse order.

%C No more terms < 10^7. - _Lars Blomberg_, Oct 06 2011

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

%e n = 22 is not a term since 12345678901112131415161718191021222 is not divisible by 22.

%e See A029495 for other examples.

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

%o (PARI) isok(n) = my(s = ""); for (k=1, n, sk = digits(k); forstep (j=#sk, 1, -1, s = concat(s, sk[j]))); (eval(s) % n) == 0; \\ _Michel Marcus_, Jan 28 2017

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

%K nonn,base,more

%O 1,2

%A _Olivier GĂ©rard_

%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(25)-a(35) from _Lars Blomberg_, Oct 06 2011

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Last modified April 24 22:17 EDT 2024. Contains 371964 sequences. (Running on oeis4.)