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A061957 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 4 (most significant digit on right). 1

%I #18 Dec 05 2020 09:34:43

%S 1,3,9,11,63,79,189,271,507,833,8697,12739,3341049

%N Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 4 (most significant digit on right).

%C This sequence differs from A029521 in that all least significant zeros are kept during concatenation.

%C No more terms < 10^7. - _Lars Blomberg_, Aug 28 2011

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

%e See A061955 for example.

%t b = 4; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[Reverse[IntegerDigits[#, b]], c], b], #] &] (* _Robert Price_, Mar 07 2020 *)

%o (PARI) lista(nn, m=4) = my(c, t); for(k=1, nn, t+=m^c*fromdigits(Vecrev(digits(k, m)), m); c+=logint(m*k, m); if(t%k==0, print1(k, ", "))); \\ _Jinyuan Wang_, Dec 05 2020

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

%K nonn,base,more

%O 1,2

%A Larry Reeves (larryr(AT)acm.org), May 24 2001

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

%E a(13) from _Lars Blomberg_, Aug 28 2011

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)