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A023234 Numbers n such that n and 9n + 4 are both prime. 4
3, 7, 11, 17, 23, 31, 37, 41, 67, 71, 73, 83, 97, 107, 113, 137, 163, 191, 193, 197, 223, 263, 283, 307, 311, 317, 337, 353, 367, 373, 401, 421, 461, 491, 577, 601, 613, 617, 631, 643, 647, 653, 661, 683, 727, 743, 751, 773, 797, 821, 823, 853, 857, 881, 883, 907, 947 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..2000

MATHEMATICA

Select[Prime[Range[1000]], PrimeQ[9 # + 4]&] (* Vincenzo Librandi, Feb 02 2014 *)

PROG

(MAGMA) [n: n in [0..1000] | IsPrime(n) and IsPrime(9*n+4)]; // Vincenzo Librandi, Nov 20 2010

CROSSREFS

Sequence in context: A081515 A289750 A184856 * A237662 A134707 A047838

Adjacent sequences:  A023231 A023232 A023233 * A023235 A023236 A023237

KEYWORD

nonn,easy

AUTHOR

David W. Wilson

STATUS

approved

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Last modified July 20 11:28 EDT 2019. Contains 325180 sequences. (Running on oeis4.)