A161996 A (negated) characteristic function of twin composite odd numbers.

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

Offset

1,1

Comments

a(n) = 0 if n is a member of A060461, otherwise a(n) = 1.

Links

Antti Karttunen, Table of n, a(n) for n = 1..37317

Index entries for characteristic functions

Mathematica

If[AllTrue[6#+{1, -1}, CompositeQ], 0, 1]&/@Range[300] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 15 2015 *)

Prog

(PARI) A161996(n) = (isprime((6*n)-1)||isprime((6*n)+1)); \\ Antti Karttunen, Dec 15 2017

Crossrefs

Cf. A060461, A100923.

Sequence in context: A015111 A014446 A014883 * A362447 A242718 A015918

Adjacent sequences: A161993 A161994 A161995 * A161997 A161998 A161999

Keyword

nonn,easy

Author

Pierre CAMI, Jun 24 2009

Extensions

Definition rephrased by R. J. Mathar, Aug 14 2009

Status

approved