A099247 Numbers such that, in binary representation, the length and the number of ones are coprime.

1, 2, 4, 5, 6, 8, 11, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 47, 55, 59, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103

Offset: 1

Author

Reinhard Zumkeller, Oct 08 2004

Keywords

• nonn
• base

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to binary expansion of n.

Crossrefs

Complement of A099248.

Cf. A070939, A000120, A007088, A099244, A099249.

Programs

Haskell

a099247 n = a099247_list !! (n-1)
a099247_list = filter ((== 1) . a099244) [1..]
-- Reinhard Zumkeller, Oct 10 2013

Mathematica

Select[Range[150],CoprimeQ[IntegerLength[#,2],DigitCount[#,2,1]]&] (* Harvey P. Dale, Sep 22 2012 *)

PARI

isok(k) = {my(b = binary(k)); gcd(#b, vecsum(b)) == 1;} \\ Amiram Eldar, Jul 26 2025

Formula

A099244(a(n)) = 1.

Extensions

Definition clarified by Harvey P. Dale, Sep 22 2012