A280999 Numbers with a prime number of 0's in their binary reflected Gray code representation.

7, 8, 12, 14, 15, 16, 17, 19, 23, 24, 25, 27, 28, 29, 30, 33, 34, 35, 36, 38, 39, 40, 44, 46, 47, 49, 50, 51, 52, 54, 55, 57, 58, 59, 61, 63, 64, 66, 68, 69, 70, 72, 73, 75, 76, 77, 78, 80, 81, 83, 87, 88, 89, 91, 92, 93, 94, 96, 98, 100, 101, 102, 104, 105, 107

Offset

1,1

Links

Indranil Ghosh, Table of n, a(n) for n = 1..10000

Wikipedia, Gray code.

Example

27 is in the sequence because the binary reflected Gray Code representation of 27 is 10110 which has 2 0's and 2 is prime.

Mathematica

Select[Range[100], PrimeQ[DigitCount[BitXor[#, Floor[#/2]], 2, 0]] &] (* Amiram Eldar, May 01 2021 *)

Prog

(PARI) is(n)=isprime(logint(n, 2)-hammingweight(bitxor(n, n>>1))+1) \\ Charles R Greathouse IV, Jan 13 2017

Crossrefs

Cf. A014550, A144754, A280998.

Sequence in context: A106630 A050798 A260628 * A024706 A050901 A105832

Adjacent sequences: A280996 A280997 A280998 * A281000 A281001 A281002

Keyword

nonn,base,easy

Author

Indranil Ghosh, Jan 12 2017

Status

approved