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A023305 Numbers n such that n remains prime through 4 iterations of function f(x) = 2x + 7. 2
293, 2063, 4583, 9203, 14723, 20123, 25733, 29453, 40253, 54713, 76103, 97523, 99833, 109433, 138683, 149993, 158243, 196853, 199403, 218873, 253103, 297623, 379913, 416963, 445463, 468113, 508073, 551963, 562403, 564713, 574703, 583733 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

n, 2*n+7, 4*n+21, 8*n+49 and 16*n+105 are primes. - Vincenzo Librandi, Aug 04 2010

LINKS

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

FORMULA

a(n) == 3 (mod 10). - John Cerkan, Oct 04 2016

PROG

(MAGMA) [n: n in [1..1000000] | IsPrime(n) and IsPrime(2*n+7) and IsPrime(4*n+21) and IsPrime(8*n+49) and IsPrime(16*n+105)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023206, A023244, A023275, and A105760.

Sequence in context: A251674 A217182 A109562 * A109182 A241047 A085502

Adjacent sequences:  A023302 A023303 A023304 * A023306 A023307 A023308

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 15 16:44 EDT 2019. Contains 327078 sequences. (Running on oeis4.)