A132194 a(n) = 1 if n-th prime is 0 or 2 mod 3, otherwise 0.

1, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0

Offset

1,1

Comments

Equivalently, a(n) = 0 if n-th prime is 1 mod 3, otherwise 1. - Wouter Meeussen, May 21 2019

Binary sequence based on the primes: play it at a slower tempo to appreciate the irregularities.

Links

G. C. Greubel, Table of n, a(n) for n = 1..10000

Formula

a(n) = 1-A099618(n). - R. J. Mathar, Jun 06 2019

Maple

a := n -> 1 - irem(modp(ithprime(n), 3), 2):
seq(a(n), n = 1..105); # Peter Luschny, May 21 2019

Mathematica

Table[If[Mod[Prime[n], 3]== 1, 0, 1], {n, 200}] (* Harvey P. Dale, May 21 2019 *)

Prog

(PARI) {a(n) = if(prime(n)%3==1, 0, 1)}; \\ G. C. Greubel, May 21 2019
(Magma) [(NthPrime(n) mod 3) eq 1 select 0 else 1: n in [1..200]]; // G. C. Greubel, May 21 2019
(Sage)
def a(n):
    if (mod(nth_prime(n), 3)==1): return 0
    else: return 1
[a(n) for n in (1..200)] # G. C. Greubel, May 21 2019

Crossrefs

Cf. A039701, A130198, A099618.

Sequence in context: A372553 A359779 A373834 * A354034 A174897 A316441

Adjacent sequences: A132191 A132192 A132193 * A132195 A132196 A132197

Keyword

nonn,easy

Author

Roger L. Bagula, Nov 05 2007

Extensions

Definition corrected by Harvey P. Dale, May 21 2019

Status

approved