The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A100923

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A100923

a(n) = 1 iff 6*n+1 and 6*n-1 are both prime numbers (0 otherwise).
(history; published version)

#4 by Alois P. Heinz at Wed Aug 04 13:53:56 EDT 2021

STATUS

proposed

approved

#3 by Georg Fischer at Wed Aug 04 13:07:57 EDT 2021

STATUS

editing

proposed

#2 by Georg Fischer at Wed Aug 04 13:07:54 EDT 2021

COMMENTS

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

CROSSREFS

Cf. A000040, A002822, A100924, A100925.

STATUS

approved

editing

#1 by N. J. A. Sloane at Sun Feb 20 03:00:00 EST 2005

NAME

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

DATA

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

1,1

EXAMPLE

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.

MATHEMATICA

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

CROSSREFS

Cf. A000040, A100924, A100925.

KEYWORD

nonn

AUTHOR

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

STATUS

approved