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A023309 Numbers n such that n remains prime through 4 iterations of function f(x) = 3x + 8. 2
3181, 9551, 22051, 30941, 32621, 61981, 76651, 99961, 134291, 151901, 163661, 185951, 226691, 227671, 240551, 288191, 342821, 374501, 394411, 402881, 423781, 426301, 446461, 456151, 459091, 460951, 554011, 572321, 577601, 617191, 653831 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

n, 3*n+8, 9*n+32, 27*n+104 and 81*n+320 are primes. - Vincenzo Librandi, Aug 04 2010

LINKS

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

FORMULA

a(n) == 1 or 31 (mod 70). - John Cerkan, Oct 04 2016

MATHEMATICA

okQ[n_]:=And@@PrimeQ/@Rest[NestList[3#+8&, n, 4]]; Select[Prime[Range[60000]], okQ] (* Harvey P. Dale, Aug 16 2010 *)

PROG

(MAGMA) [n: n in [1..1000000] | IsPrime(n) and IsPrime(3*n+8) and IsPrime(9*n+32) and IsPrime(27*n+104) and IsPrime(81*n+320)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023210, A023248, and A023279.

Sequence in context: A020420 A155484 A129472 * A023337 A236131 A205034

Adjacent sequences:  A023306 A023307 A023308 * A023310 A023311 A023312

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified June 26 20:37 EDT 2019. Contains 324380 sequences. (Running on oeis4.)