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A023271 Primes p such that p, p+6, p+12, p+18 are all primes. 15
5, 11, 41, 61, 251, 601, 641, 1091, 1481, 1601, 1741, 1861, 2371, 2671, 3301, 3911, 4001, 5101, 5381, 5431, 5641, 6311, 6361, 9461, 11821, 12101, 12641, 13451, 14621, 14741, 15791, 15901, 17471, 18211, 19471, 20341, 21481, 23321, 24091, 26171, 26681 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Smallest member of a "sexy" prime quadruple.

For n > 1, a(n) ends in 1. - Robert Israel, Jul 16 2015

LINKS

Matt C. Anderson and Robert Israel, Table of n, a(n) for n = 1..10000 (n = 1..100 from Matt C. Anderson)

Eric Weisstein's World of Mathematics, Sexy Primes.

MAPLE

for a to 2*10^5 do

if `and`(isprime(a), isprime(a+6), isprime(a+12), isprime(a+18))

then print(a);

end if;

end do;

# code produces 109 primes

# Matt C. Anderson, Jul 15 2015

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[p+6]&&PrimeQ[p+12]&&PrimeQ[p+18], AppendTo[lst, p]], {n, 8!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 29 2008 *)

Select[Range[30000], PrimeQ[#] && PrimeQ[# + 6] && PrimeQ[# + 12] && PrimeQ[# + 18] &] (* Vincenzo Librandi, Jul 15 2015 *)

PROG

(MAGMA) [p: p in PrimesInInterval(2, 1000000) | forall{i: i in [ 6, 12, 18] | IsPrime(p+i)}]; // Vincenzo Librandi, Jul 15 2015

(PARI) main(size)=my(v=vector(size), i, r=1, p); for(i=1, size, while(1, p=prime(r); if(isprime(p+6)&&isprime(p+12)&&isprime(p+18), v[i]=p; r++; break, r++))); v \\ Anders Hellström, Jul 16 2015

CROSSREFS

Cf. A023201, A046117, A046122, A046123, A046124.

Sequence in context: A154297 A089441 A046121 * A159049 A047976 A006382

Adjacent sequences:  A023268 A023269 A023270 * A023272 A023273 A023274

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

Edited by N. J. A. Sloane, Aug 04 2009 following a suggestion from Daniel Forgues

STATUS

approved

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Last modified July 31 15:11 EDT 2015. Contains 260166 sequences.