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A023258 Numbers n such that n remains prime through 2 iterations of function f(x) = 6x + 7. 2
5, 17, 29, 37, 89, 127, 199, 229, 269, 347, 359, 379, 397, 499, 769, 809, 929, 947, 977, 1049, 1087, 1129, 1277, 1279, 1367, 1409, 1439, 1489, 1499, 1607, 1609, 1787, 2017, 2039, 2089, 2399, 2539, 2707, 2819, 2837, 2957, 3089, 3109, 3217, 3229, 3389, 3499 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that n, 6*n+7 and 36*n+49 are primes. - Vincenzo Librandi, Aug 04 2010

LINKS

John Cerkan, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = 7 or 9 (mod 10) for n > 1. - John Cerkan, Sep 14 2016

PROG

(MAGMA) [n: n in [1..100000] | IsPrime(n) and IsPrime(6*n+7) and IsPrime(36*n+49)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023222, A153218. - John Cerkan, Sep 14 2016

Sequence in context: A068829 A090403 A096705 * A030554 A017581 A068230

Adjacent sequences:  A023255 A023256 A023257 * A023259 A023260 A023261

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified June 24 17:50 EDT 2019. Contains 324330 sequences. (Running on oeis4.)