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A027704 Numbers k such that the k-th prime has an even number of 1's in its binary expansion and the (k+1)st prime has an odd number of 1's. 3
3, 7, 10, 14, 16, 20, 24, 26, 30, 35, 38, 45, 57, 60, 62, 64, 66, 72, 74, 77, 79, 87, 89, 92, 97, 99, 101, 105, 109, 114, 117, 122, 125, 131, 133, 137, 139, 142, 148, 150, 152, 155, 159, 166, 170, 173, 176, 178, 185, 187, 190, 194, 201, 203, 206, 209, 211, 215, 223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

Primes:= [seq(ithprime(i), i=1..100)]:

Q:= map(t -> convert(convert(t, base, 2), `+`) mod 2, Primes):

DQ:= Q[2..-1]-Q[1..-2]:

select(t -> DQ[t] = 1, [$1..nops(DQ)]); # Robert Israel, Mar 27 2018

PROG

(PARI) isok(n) = my(p=prime(n)); !(hammingweight(p) % 2) && (hammingweight(nextprime(p+1)) % 2); \\ Michel Marcus, Mar 29 2018

CROSSREFS

Cf. A027703 (corresponding primes).

Cf. A027702, A027704, A027706.

Cf. A027701, A027703, A027705.

Sequence in context: A289167 A289114 A289027 * A288999 A310187 A198268

Adjacent sequences:  A027701 A027702 A027703 * A027705 A027706 A027707

KEYWORD

nonn,easy,base

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Erich Friedman

STATUS

approved

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Last modified January 25 02:37 EST 2022. Contains 350565 sequences. (Running on oeis4.)