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A029471 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 2 (most significant digit on left). 141

%I

%S 1,85,145,245,1189,356717,19590671,35741759

%N Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 2 (most significant digit on left).

%C No other terms below 10^8.

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

%t b = 2; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[IntegerDigits[#, b], c], b], #] &] (* _Robert Price_, Mar 12 2020 *)

%o (Python)

%o from itertools import count

%o def a029471():

%o total = 0

%o power_of_two = 1

%o index_of_two = 0

%o length_of_string = 0

%o for n in count(1):

%o total += (n<<length_of_string)

%o if n == power_of_two:

%o power_of_two *= 2

%o index_of_two += 1

%o length_of_string += index_of_two

%o if total % n == 0:

%o yield n

%o # _Christian Perfect_, Feb 07 2014

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

%K nonn,base,hard,more

%O 1,2

%A _Olivier GĂ©rard_

%E One more term from Larry Reeves (larryr(AT)acm.org), Dec 03 2001

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

%E a(7)-a(8) from _Max Alekseyev_, May 12 2011

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Last modified May 29 07:41 EDT 2020. Contains 334697 sequences. (Running on oeis4.)