



1, 2, 3, 4, 5, 6, 7, 12, 45, 64, 121, 144, 238, 261, 415, 2296, 2847
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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?


LINKS

Table of n, a(n) for n=1..17.


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

Cf. A002110, A006450.
Sequence in context: A173819 A165305 A125745 * A032990 A060810 A319723
Adjacent sequences: A265121 A265122 A265123 * A265125 A265126 A265127


KEYWORD

nonn,more


AUTHOR

Altug Alkan, Dec 02 2015


STATUS

approved



