A027703 Primes with even number of 1's in binary expansion such that next prime has odd number of 1's.

5, 17, 29, 43, 53, 71, 89, 101, 113, 149, 163, 197, 269, 281, 293, 311, 317, 359, 373, 389, 401, 449, 461, 479, 509, 523, 547, 571, 599, 619, 643, 673, 691, 739, 751, 773, 797, 821, 857, 863, 881, 907, 937, 983, 1013, 1031, 1049, 1061, 1103, 1117, 1151

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..2500

Formula

a(n) = prime(A027704(n)). - Michel Marcus, Mar 29 2018

Mathematica

c[ n_ ] := OddQ[ Count[ IntegerDigits[ n, 2 ], 1 ] ]; Map[ Prime, Select[ Range[ 300 ], Not[ c[ Prime[ # ] ] ]&&c[ Prime[ #+1 ] ]& ] ]
Prime[#]&/@SequencePosition[Table[If[EvenQ[DigitCount[n, 2, 1]], 1, 0], {n, Prime[ Range[200]]}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 03 2019 *)

Crossrefs

Cf. A027704.

Cf. A027701, A027705, A027707.

Sequence in context: A145475 A071695 A242025 * A075695 A146278 A034937

Adjacent sequences: A027700 A027701 A027702 * A027704 A027705 A027706

Keyword

nonn,easy

Author

N. J. A. Sloane.

Extensions

More terms from Erich Friedman.

Offset changed by Michel Marcus, Mar 29 2018

Status

approved