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
Keywords
Examples
5 is in this sequence because 5 is prime and neither 5 - 4 = 1 nor 5 + 4 = 9 is prime.
Programs
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Magma
[p: p in PrimesUpTo(620) | not IsPrime(p-4) and not IsPrime(p+4)];
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Mathematica
Select[Prime[Range[125]], Not[PrimeQ[# - 4]] && Not[PrimeQ[# + 4]] &] (* Alonso del Arte, May 30 2014 *)
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PARI
select(n->!isprime(n-4) && !isprime(n+4), primes(200)) \\ Charles R Greathouse IV, May 29 2014
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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
Formula
a(n) ~ n log n. - Charles R Greathouse IV, May 29 2014