A100923 a(n) = 1 iff 6*n+1 and 6*n-1 are both prime numbers (0 otherwise).

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

Offset: 1

Author

Joseph Biberstine (jrbibers(AT)indiana.edu), Nov 22 2004

Keywords

• nonn

Comments

Characteristic function of A002822. - Georg Fischer, Aug 04 2021

Examples

			a(3) = 1 because 6*3-1=17 and 6*3+1=19 are both prime.
a(4) = 0 because 6*4-1=23 is prime and 6*4+1=25 is not prime.
a(20) = 0 because 6*20-1=119 and 6*20+1=121 are both not prime.
		

Crossrefs

Cf. A000040, A002822, A100924, A100925.

Programs

Mathematica

Table[If[And[PrimeQ[6*k - 1], PrimeQ[6*k + 1]], 1, 0], {k, 1, 110}]