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A023259 Numbers n such that n remains prime through 2 iterations of function f(x) = 7x + 6. 4
5, 11, 31, 59, 61, 71, 149, 179, 269, 439, 499, 541, 571, 719, 761, 1049, 1091, 1181, 1319, 1451, 1489, 1579, 1601, 1831, 1861, 1879, 1949, 2069, 2089, 2269, 2311, 2389, 2441, 2621, 2699, 2819, 2851, 2909, 3001, 3079, 3119, 3391, 3529, 3631, 3701, 3709 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that n, 7*n+6 and 49*n+48 are primes. - Vincenzo Librandi, Aug 04 2010

LINKS

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

FORMULA

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

PROG

(MAGMA) [n: n in [1..100000] | IsPrime(n) and IsPrime(7*n+6) and IsPrime(49*n+48)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023225, A024900. - John Cerkan, Sep 14 2016

Sequence in context: A045453 A052228 A105910 * A267478 A280081 A057470

Adjacent sequences:  A023256 A023257 A023258 * A023260 A023261 A023262

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified June 20 19:36 EDT 2019. Contains 324234 sequences. (Running on oeis4.)