A243012 Odd primes p such that neither p - 4 nor p + 4 is prime.

5, 29, 31, 53, 59, 61, 73, 89, 137, 139, 149, 151, 157, 173, 179, 181, 191, 199, 211, 239, 241, 251, 257, 263, 269, 271, 283, 293, 331, 337, 347, 359, 367, 373, 389, 409, 419, 421, 431, 433, 449, 479, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 619

Offset

1,1

Links

Table of n, a(n) for n=1..58.

Formula

a(n) ~ n log n. - Charles R Greathouse IV, May 29 2014

Example

5 is in this sequence because 5 is prime and neither 5 - 4 = 1 nor 5 + 4 = 9 is prime.

Mathematica

Select[Prime[Range[125]], Not[PrimeQ[# - 4]] && Not[PrimeQ[# + 4]] &] (* Alonso del Arte, May 30 2014 *)

Prog

(Magma) [p: p in PrimesUpTo(620) | not IsPrime(p-4) and not IsPrime(p+4)];
(PARI) select(n->!isprime(n-4) && !isprime(n+4), primes(200)) \\ Charles R Greathouse IV, May 29 2014
(Sage) [p for p in primes(5, 700) if not is_prime(p-4) and not is_prime(p+4)] # Bruno Berselli, Jun 10 2014

Crossrefs

Cf. A007510, A140546.

Sequence in context: A001990 A043062 A321701 * A053244 A096696 A115279

Adjacent sequences: A243009 A243010 A243011 * A243013 A243014 A243015

Keyword

nonn

Author

Juri-Stepan Gerasimov, May 28 2014

Status

approved