A296028 Characteristic function of primes in the nonmultiples of 3.

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

Offset

1

Links

Table of n, a(n) for n=1..105.

Formula

From David A. Corneth, Dec 03 2017: (Start)

a(n) = A010051(A001651(n)).

a(n) = 1 if (6n - 3 - (-1)^n)/4 is prime, otherwise a(n) = 0. (End)

Example

a(2) = 1 because the 2nd nonmultiple of 3 is 2, which is prime.

Maple

f:= n -> charfcn[{true}](isprime(floor((3*n-1)/2))):
map(f, [$1..1000]); # Robert Israel, Jan 24 2018

Mathematica

Array[Boole@ PrimeQ@ Floor[(3 # - 1)/2] &, 105] (* Michael De Vlieger, Dec 03 2017 *)

Prog

(PARI) a(n) = isprime(floor((3*n-1)/2)) \\ Iain Fox, Dec 03 2017
(PARI) first(n) = {my(inc = t = 1, res = vector(n)); for(i = 1, n, res[i] = isprime(t); t += inc; inc = 3-inc); res} \\ David A. Corneth, Dec 03 2017

Crossrefs

Cf. A001651, A010051, A045344.

Sequence in context: A189017 A189132 A189203 * A165263 A108737 A165221

Adjacent sequences: A296025 A296026 A296027 * A296029 A296030 A296031

Keyword

nonn

Author

Martin Michael Musatov, Dec 03 2017

Status

approved