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A161399 a(n) = the smallest divisor of n that contains the same number of (non-leading) 0's as n when both numbers are written in binary. 2
1, 2, 1, 4, 5, 2, 1, 8, 9, 10, 11, 4, 13, 2, 1, 16, 17, 18, 19, 20, 21, 22, 23, 8, 25, 26, 27, 4, 29, 2, 1, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 9, 46, 47, 16, 49, 50, 51, 52, 53, 9, 5, 8, 19, 58, 59, 4, 61, 2, 1, 64, 65, 66, 67, 68, 69, 70, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Paul Tek, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory):

z:= proc(n) local m, r; m, r:=n, 0;

      while m>1 do r:= r+1-irem(m, 2, 'm'); r od

    end:

a:= proc(n) local d, t; t:=z(n);

      for d in sort([divisors(n)[]]) do

        if z(d)=t then return d fi od

    end:

seq(a(n), n=0..100);  # Alois P. Heinz, Jun 23 2013

MATHEMATICA

sdn[n_]:=SelectFirst[Divisors[n], DigitCount[#, 2, 0]==DigitCount[n, 2, 0]&]; Array[sdn, 80] (* The program uses the SelectFirst function from Mathematica version 10 *) (* Harvey P. Dale, Sep 05 2015 *)

CROSSREFS

Cf. A161398.

Sequence in context: A090077 A229763 A163509 * A318479 A053985 A091564

Adjacent sequences:  A161396 A161397 A161398 * A161400 A161401 A161402

KEYWORD

base,nonn

AUTHOR

Leroy Quet, Jun 09 2009

STATUS

approved

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Last modified August 5 08:27 EDT 2021. Contains 346464 sequences. (Running on oeis4.)