A027702 Numbers k such that the k-th prime has an even number of 1's in binary expansion and the (k+1)st prime also has an even number of 1's.

2, 9, 23, 34, 55, 56, 59, 68, 69, 70, 71, 76, 91, 96, 108, 124, 141, 146, 147, 154, 165, 182, 183, 184, 199, 200, 208, 213, 214, 221, 222, 225, 226, 227, 236, 239, 240, 245, 252, 255, 256, 269, 280, 283, 286, 289, 290, 291, 292, 327, 339, 355, 356, 359, 365, 393, 396, 397, 406, 414, 419, 420

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

Select[Range[1000], EvenQ[DigitCount[Prime[ # ], 2][[1]]] && EvenQ[DigitCount[Prime[ # + 1], 2][[1]]] &] (* Stefan Steinerberger, Apr 21 2006 *)

Prog

(PARI) is(n)=my(p=prime(n)); hammingweight(p)%2==0 && hammingweight(nextprime(p+1))%2==0 \\ Charles R Greathouse IV, Mar 29 2013

Crossrefs

Sequence in context: A368626 A032149 A032054 * A051897 A209294 A294870

Adjacent sequences: A027699 A027700 A027701 * A027703 A027704 A027705

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Scott Lindhurst (ScottL(AT)alumni.princeton.edu)

Status

approved