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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, 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 (list; graph; refs; listen; history; text; internal format)
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 * A242718 A015918 A016056

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

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Last modified February 17 02:22 EST 2020. Contains 331976 sequences. (Running on oeis4.)