A175416 Those positive integers n that when written in binary, each run of 0's and 1's has a length which is coprime to the number of binary digits of n.

1, 2, 4, 5, 6, 8, 10, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 42, 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

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..5000

Example

70 in binary is 1000110. There is a run of one 1, followed by a run of three 0's, followed by a run of two 1's, followed finally by a run of one 0. And there are seven binary digits all together. Since 1, 3, 2, and 1 each are coprime to 7, then 70 is in the sequence.

Mathematica

cpQ[n_]:=Module[{d=Length/@Split[IntegerDigits[n, 2]]}, And@@CoprimeQ[ d, Total[ d]]]; Select[Range[100], cpQ] (* Harvey P. Dale, Mar 25 2013 *)

Crossrefs

Cf. A175415

Sequence in context: A020640 A068383 A276603 * A190854 A362942 A069872

Adjacent sequences: A175413 A175414 A175415 * A175417 A175418 A175419

Keyword

base,nonn

Author

Leroy Quet, May 07 2010

Extensions

More terms from Sean A. Irvine, Mar 02 2011

Status

approved