A265124 Integers n such that A002110(n) + A006450(n) is prime.

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

Offset: 1

Author

Altug Alkan, Dec 02 2015

Keywords

• nonn
• more

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?

Examples

			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.
		

Crossrefs

Cf. A002110, A006450.

Programs

Mathematica

Select[Range@ 500, PrimeQ[Product[Prime@ k, {k, #}] + Prime@ Prime@ #] &] (* Michael De Vlieger, Dec 02 2015 *)

PARI

lista(nn) = {s = 1; for(k=1, nn, s *= prime(k); if(ispseudoprime(s + prime(prime(k))), print1(k, ", ")); ); }