A118859 - OEIS

A118859

Numbers k such that k-1, k+1, 2*k-1, 2*k+1, 3*k-1 and 3*k+1 are primes.

6, 53550, 420420, 422310, 1624350, 2130240, 3399900, 5199810, 5246010, 6549270, 7384440, 7775880, 9516570, 9565710, 10430280, 11845260, 13207950, 14562870, 14619990, 18747960, 20099940, 21596820, 21968100, 24358950, 24610740, 26916120, 28359240, 30838080

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

6 is there because 5, 7, 11, 13, 17, 19 are all prime.

MATHEMATICA

Select[Range[25*10^6], AllTrue[Flatten[{#+{1, -1}, 2#+{1, -1}, 3#+{1, -1}}], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 13 2016 *)

CROSSREFS

Cf. A014574, A066388, A118860, A349321, A348348.

Sequence in context: A353033 A289391 A295817 * A323725 A259162 A076913

Adjacent sequences: A118856 A118857 A118858 * A118860 A118861 A118862

KEYWORD

nonn

AUTHOR

Labos Elemer, May 03 2006

EXTENSIONS

Edited by Don Reble, May 16 2006

a(26)-a(28) from Jon E. Schoenfield, Dec 07 2021

STATUS

approved