A167021 a(n) = 1 iff 6n+1 is prime.

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

Offset: 1

Author

Washington Bomfim, Oct 27 2009

Keywords

• nonn

Examples

			a(3) = 1 because 6*3+1 is prime;
a(4) = 0 since 6*4+1 is composite.
		

Links

• Index entries for characteristic functions

Crossrefs

Cf. A024899, A167020, A132350. For n < 14, a(n) = A132350(n).

Programs

Magma

[IsPrime(6*n+1) select 1 else 0:n in [1..105]]; // Marius A. Burtea, Oct 06 2019

Mathematica

If[PrimeQ[6#+1],1,0]&/@Range[120] (* Harvey P. Dale, Apr 03 2012 *)

PARI

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