OFFSET
1,1
COMMENTS
Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019
a(32) > 180000. - Tyler Busby, Mar 29 2024
EXAMPLE
Prime 7 is a term because primorial(7)/2 - 2 = A034386(7)/2 - 2 = 2*3*5*7/2 - 2 = 103 is prime.
MAPLE
b:= proc(n) b(n):= `if`(n=0, 1, `if`(isprime(n), n, 1)*b(n-1)) end:
q:= p-> isprime(p) and isprime(b(p)/2-2):
select(q, [$1..500])[];
MATHEMATICA
k = 1; Do[k *= Prime[n]; If[PrimeQ[k - 2], Print[Prime[n]]], {n, 2, 3276}] (* Ryan Propper, Oct 25 2005 *&)
Prime[#]&/@Flatten[Position[FoldList[Times, Prime[Range[1000]]]/2-2, _?PrimeQ]] (* Harvey P. Dale, Jun 09 2023 *)
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Hugo Pfoertner, Jun 27 2004
EXTENSIONS
5 more terms from Ryan Propper, Oct 25 2005
a(29)-a(31) from Tyler Busby, Mar 16 2024
STATUS
approved