A260376 Values of n such that prime(prime(n)) + n is a prime number.

2, 6, 16, 20, 30, 42, 78, 90, 92, 102, 108, 118, 124, 126, 128, 132, 136, 150, 160, 166, 180, 182, 186, 194, 196, 202, 206, 210, 214, 230, 270, 280, 294, 348, 356, 358, 366, 370, 374, 378, 418, 436, 456, 458, 472, 474, 478, 492, 522, 546, 556, 560, 570, 584, 586, 590

Offset

1,1

Comments

Inspired by A061068.

Obviously, sequence only can include even numbers.

Initial primes of the form prime(prime(n)) + n are 7, 47, 257, 373, 647, 1129, 2797, 3389, 3499, 4129, 4447.

Links

Table of n, a(n) for n=1..56.

Example

For n=2, prime(prime(2)) + 2 = prime(3) + 2 = 7. 7 is a prime number.

Mathematica

Select[Range[600], PrimeQ[Prime[Prime[#]] + #] &] (* Vincenzo Librandi, Aug 30 2015 *)

Prog

(PARI) for(n=1, 1e3, if(isprime(prime(prime(n))+n), print1(n", ")))
(Magma) [n: n in [1..600] | IsPrime(NthPrime(NthPrime(n))+n)]; // Vincenzo Librandi, Aug 30 2015
(Perl) use ntheory ":all"; my @p = grep { is_prime(nth_prime(nth_prime($_))+$_) } 1..10000; say join ", ", @p; # Dana Jacobsen, Sep 02 2015

Crossrefs

Cf. A006450.

Sequence in context: A080622 A082374 A085226 * A330866 A071522 A192532

Adjacent sequences: A260373 A260374 A260375 * A260377 A260378 A260379

Keyword

nonn,easy

Author

Altug Alkan, Aug 29 2015

Status

approved