A133410 Least prime p such that p-6*n is prime.

2, 11, 17, 23, 29, 37, 41, 47, 53, 59, 67, 71, 79, 83, 89, 97, 101, 107, 113, 127, 127, 131, 137, 149, 149, 157, 163, 167, 173, 179, 191, 191, 197, 211, 211, 223, 223, 227, 233, 239, 251, 251, 257, 263, 269, 277, 281, 293, 293, 307, 307, 311, 317, 331, 331, 337

Offset: 0

Author

Pierre CAMI, Nov 25 2007

Keywords

• nonn

Comments

If duplicates are omitted, this is the sequence of primes p such that all p - phi(k) - 1 are composite for 1 <= phi(k)-1 < p. - Michel Lagneau, Sep 14 2012

If duplicates are omitted, the given entries equal A025584 (p: p-2 is not a prime) except A025584 includes 3 (since 1 is not prime). - Harry G. Coin, Nov 29 2015

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A025584, A067829 (complement w.r.t. primes), A133387.

Programs

Maple

Primes:= select(isprime,{2,seq(i,i=3..10^4,2)}):
seq(min(Primes intersect map(`+`,Primes,6*n)),n=0..1000); # Robert Israel, Nov 30 2015

Mathematica

a={};Do[i=6*n+1; While[Not[PrimeQ[i]&&PrimeQ[i-6*n]],i++ ];AppendTo[a,i],{n,0,60}]; a (* Stefan Steinerberger, Nov 26 2007 *)
Table[Module[{p=NextPrime[6n]},While[!PrimeQ[p-6n],p=NextPrime[p]];p],{n,0,60}] (* Harvey P. Dale, Apr 07 2025 *)

PARI

a(n) = {k=1; while(k, if(ispseudoprime(prime(k)-6*n), return(prime(k))); k++)} \\ Altug Alkan, Dec 04 2015

Extensions

More terms from Stefan Steinerberger, Nov 26 2007