

A079139


Numbers n such that (Product of first n twin prime pair averages [A014574] ) + 1 is prime.


1




OFFSET

1,2


COMMENTS

a(3) and a(4) certified prime with Primo.


LINKS



EXAMPLE

a(2) = 5 because the product of the first five terms of A014574 + 1, 4*6*12*18*30 + 1 = 155521, is prime.


MATHEMATICA

seq = {1}; prod = 4; k = 1; Do[If[AllTrue[6 n + {1, 1}, PrimeQ], prod *= 6 n; k++; If[PrimeQ[prod + 1], AppendTo[seq, k]]], {n, 1, 5000}]; seq (* Amiram Eldar, Dec 14 2019 *)


PROG

(PARI) { atp(N)= local(t, c); t=1; c=0; forprime(p=2, N, if(isprime(p+2), t*=p+1; c++; if(isprime(t+1), print1(c, ", ")))) }


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



