OFFSET
1,2
COMMENTS
Corresponding primes are 5, 11, 41, 227, 2341 and 30071.
1, 4, 64, 121, 144 are squares for initial terms of sequence. Are there any other squares in this sequence?
EXAMPLE
a(1) = 1 because 2 + 3 = 5 is prime.
a(2) = 2 because 2*3 + 5 = 11 is prime.
a(3) = 3 because 2*3*5 + 11 = 41 is prime.
MATHEMATICA
Select[Range@ 500, PrimeQ[Product[Prime@ k, {k, #}] + Prime@ Prime@ #] &] (* Michael De Vlieger, Dec 02 2015 *)
PROG
(PARI) lista(nn) = {s = 1; for(k=1, nn, s *= prime(k); if(ispseudoprime(s + prime(prime(k))), print1(k, ", ")); ); }
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Altug Alkan, Dec 02 2015
STATUS
approved