login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A023279 Numbers n such that n remains prime through 3 iterations of function f(x) = 3x + 8. 3
11, 31, 211, 1151, 3181, 5051, 5261, 6101, 6661, 9391, 9551, 10501, 11701, 13171, 15901, 16481, 19531, 22051, 24181, 26261, 27031, 28351, 28591, 28661, 29411, 30941, 31321, 32621, 38011, 40471, 42101, 48371, 49921, 57571, 59791, 61981, 66161, 67271 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

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

FORMULA

a(n) == 1 (mod 10). - John Cerkan, Sep 16 2016

MATHEMATICA

Select[Prime@ Range@ 7000, Times @@ Boole@ PrimeQ@ Rest@ NestList[3 # + 8 &, #, 3] > 0 &] (* Michael De Vlieger, Sep 19 2016 *)

PROG

(MAGMA) [n: n in [1..150000] | IsPrime(n) and IsPrime(3*n+8) and IsPrime(9*n+32) and IsPrime(27*n+104)] // Vincenzo Librandi, Aug 04 2010

(PARI) is(n)=isprime(n) && isprime(3*n+8) && isprime(9*n+32) && isprime(27*n+104) \\ Charles R Greathouse IV, Sep 20 2016

CROSSREFS

Subsequence of A023210 and of A023248.

Sequence in context: A128337 A093382 A098264 * A068715 A093881 A328715

Adjacent sequences:  A023276 A023277 A023278 * A023280 A023281 A023282

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 29 08:08 EST 2020. Contains 331337 sequences. (Running on oeis4.)