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A239734 Primes p such that 8p+9 and 9p+8 are both prime. 1
11, 29, 71, 79, 151, 211, 251, 401, 419, 461, 541, 599, 601, 659, 881, 1129, 1231, 1381, 1831, 1901, 2309, 2521, 2741, 2851, 2879, 2969, 3011, 3121, 3301, 3319, 3511, 3581, 3719, 3761, 3779, 3851, 4099, 4241, 4561, 4649, 4691, 4969, 5021, 5209, 5531, 5641 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All of the numbers in this sequence are congruent to either 1 or 9 mod 10.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

11 is prime, 11*8+9 = 97 is prime, and 9*11+8 = 107 is prime. Thus, 11 is a member of this sequence.

MATHEMATICA

Select[Prime[Range[800]], AllTrue[{8#+9, 9#+8}, PrimeQ]&] (* The program uses the function AllTrue from Mathematica version 10 *) (* Harvey P. Dale, Aug 20 2014 *)

PROG

(Python)

import sympy

from sympy import isprime

{print(n) for n in range(5000) if isprime(8*n+9) and isprime(9*n+8) and isprime(n)}

(PARI) s=[]; forprime(p=2, 6000, if(isprime(8*p+9) && isprime(9*p+8), s=concat(s, p))); s \\ Colin Barker, Mar 26 2014

CROSSREFS

Sequence in context: A216296 A099909 A106881 * A106880 A275475 A135064

Adjacent sequences:  A239731 A239732 A239733 * A239735 A239736 A239737

KEYWORD

nonn,easy

AUTHOR

Derek Orr, Mar 25 2014

STATUS

approved

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Last modified May 26 19:20 EDT 2019. Contains 323597 sequences. (Running on oeis4.)