A178648 Primes p such that primorial(p)/2 +- 2 are primes.

5, 7, 13, 31

Offset

1,1

Comments

No further terms up to the 500th prime, i.e., 3571. - Harvey P. Dale, May 09 2023

Links

Table of n, a(n) for n=1..4.

Carlos Rivera, Puzzle 974. More twins like these..., The Prime Puzzles & Problems Connection.

Example

3*5 = 15; 15-2 and 15+2 are primes.

Mathematica

pp=1; lst={}; Do[p=Prime[n]; pp*=p; If[PrimeQ[pp-2]&&PrimeQ[pp+2], Print[Date[], p]; AppendTo[lst, p]], {n, 2, 4!}]; lst
Module[{nn=15, pr, pm}, pr=Prime[Range[nn]]; pm=FoldList[Times, pr]; Select[Thread[ {pr, pm}], AllTrue[ #[[2]]/2+{2, -2}, PrimeQ]&]][[;; , 1]] (* Harvey P. Dale, May 09 2023 *)

Crossrefs

Cf. A070826, A178641, A178642.

Intersection of A096177 and A096547.

Sequence in context: A090610 A230115 A182342 * A241859 A293059 A179625

Adjacent sequences: A178645 A178646 A178647 * A178649 A178650 A178651

Keyword

nonn,more

Author

Vladimir Joseph Stephan Orlovsky, May 31 2010

Status

approved