A167020 a(n) = 1 iff 6n-1 is prime.

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

Offset: 1

Author

Washington Bomfim, Oct 27 2009

Keywords

• nonn

Examples

			a(5) = 1 because 6*5-1 is prime, a(6) = 0 since 6*6-1 is composite.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..5000
• Index entries for characteristic functions

Crossrefs

Cf. A024898, A167021.

Programs

Magma

[IsPrime(6*n-1) select 1 else 0: n in[1..100]]; // Vincenzo Librandi, Jan 19 2019

Mathematica

Table[If[PrimeQ[6 n - 1], 1, 0], {n, 100}] (* Vincenzo Librandi, Jan 19 2019 *)

PARI

a(n) = isprime(6*n-1); \\ Michel Marcus, Jan 19 2019