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 A065879 Lowest positive number that is n times the number of 1's in its binary expansion, or 0 if no such number exists. 5

%I

%S 1,2,6,4,10,12,21,8,18,20,55,24,0,42,60,16,34,36,0,40,126,110,69,48,0,

%T 0,81,84,116,120,155,32,66,68,0,72,185,0,156,80,205,252,172,220,180,

%U 138,0,96,0,0,204,0,212,162,0,168,228,232,295,240,366,310,378,64,130

%N Lowest positive number that is n times the number of 1's in its binary expansion, or 0 if no such number exists.

%C a(n) is bounded above by n*A272756(n), so a program only has to check values up to that point to see if a(n) is zero. - _Peter Kagey_, May 05 2016

%H Peter Kagey, <a href="/A065879/b065879.txt">Table of n, a(n) for n = 1..10000</a>

%e a(23) is 69 since 69 is written in binary as 1000101, 69/(1+0+0+0+1+0+1)=23 and there is no lower possibility (neither 23 nor 46 are divisible by their number of binary 1's).

%t Table[SelectFirst[Range[2^12], # == n First@ DigitCount[#, 2] &] /. k_ /; MissingQ@ k -> 0, {n, 80}] (* _Michael De Vlieger_, May 05 2016, Version 10.2 *)

%Y A003634 is the base 10 equivalent.

%Y Cf. A000120, A049445, A058898, A065413, A065878, A065880, A272756.

%K base,nonn

%O 1,2

%A _Henry Bottomley_, Nov 26 2001

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Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)