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!)
A023286 Numbers n such that n remains prime through 3 iterations of function f(x) = 5x + 8. 3
7, 13, 43, 223, 757, 883, 2143, 2269, 2521, 2917, 3253, 3967, 4297, 4423, 6229, 6427, 6679, 7621, 7741, 10429, 11353, 12739, 14593, 14929, 15259, 15541, 15937, 16981, 17449, 17911, 21187, 23899, 24697, 25633, 27481, 28789, 29611, 29833, 30253, 30703 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that n, 5*n+8, 25*n+48 and 125*n+248 are primes. - Vincenzo Librandi, Aug 04 2010

LINKS

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

FORMULA

a(n) == 1 (mod 6). - John Cerkan, Sep 21 2016

MATHEMATICA

it3Q[n_]:=AllTrue[Rest[NestList[5#+8&, n, 3]], PrimeQ]; Select[ Prime[ Range[ 3500]], it3Q] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jul 21 2015 *)

PROG

(MAGMA) [n: n in [1..150000] | IsPrime(n) and IsPrime(5*n+8) and IsPrime(25*n+48) and IsPrime(125*n+248)] // Vincenzo Librandi, Aug 04 2010

CROSSREFS

Subsequence of A023220, A023255, and A111225.

Sequence in context: A139403 A087820 A272032 * A287685 A159305 A146648

Adjacent sequences:  A023283 A023284 A023285 * A023287 A023288 A023289

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 February 18 02:57 EST 2020. Contains 332006 sequences. (Running on oeis4.)