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.
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
Offset: 1
Links
- Paul Tek, Table of n, a(n) for n = 1..10000
Crossrefs
Cf. A161398.
Programs
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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 *)