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

5, 7, 13, 31

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, May 31 2010

Keywords

• nonn
• more

Comments

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

Examples

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

Links

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

Crossrefs

Cf. A070826, A178641, A178642.

Intersection of A096177 and A096547.

Programs

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 *)