

A067774


Primes p such that p+2 is not a prime.


17



2, 7, 13, 19, 23, 31, 37, 43, 47, 53, 61, 67, 73, 79, 83, 89, 97, 103, 109, 113, 127, 131, 139, 151, 157, 163, 167, 173, 181, 193, 199, 211, 223, 229, 233, 241, 251, 257, 263, 271, 277, 283, 293, 307, 313, 317, 331, 337, 349, 353, 359, 367, 373, 379, 383, 389
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OFFSET

1,1


COMMENTS

Primes n such that n!*B(n+1) is an integer where B(k) are the Bernoulli numbers.
All primes except for the lower members of twin primes  i.e. remove 3, 5, 11, 17, 29, 41, 59, 71, 101, 107, 137, ...  Gerard Schildberger, Feb 13 2005


LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000


FORMULA

Except for a(1)=2, a(n+1)=A049591(n).
a(n) ~ n log n.  Charles R Greathouse IV, Jul 01 2013


MATHEMATICA

f[n_]:=PrimeQ[n+2]; lst={}; Do[p=Prime[n]; If[ !f[p], AppendTo[lst, p]], {n, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Oct 17 2009 *)


PROG

(MAGMA) [p: p in PrimesUpTo(400)  NextPrime(p)p ne 2]; // Bruno Berselli, Apr 09 2013
(PARI) is(n)=isprime(n)&&!isprime(n+2) \\ Charles R Greathouse IV, Jul 01 2013


CROSSREFS

Cf. A049591.
Complement of A001359 in A000040, A025584, A007510.
Sequence in context: A155547 A007821 A156007 * A063637 A216526 A020623
Adjacent sequences: A067771 A067772 A067773 * A067775 A067776 A067777


KEYWORD

nonn,easy


AUTHOR

Benoit Cloitre, Feb 06 2002


EXTENSIONS

Better description from Vladeta Jovovic, Dec 14 2002


STATUS

approved



