A165557 Primes of the form (p^2-1)/4-p where p are also primes.

5, 19, 29, 71, 109, 181, 379, 419, 811, 1259, 1481, 2549, 2861, 3079, 4159, 4691, 7309, 8009, 8929, 13339, 17029, 18089, 19739, 21169, 23869, 24179, 27059, 35531, 37441, 39799, 41411, 43889, 46439, 47741, 48619, 53129, 59779, 61751, 67339, 89101, 93329

Offset

1,1

Comments

The associated primes p are in A165349.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

a(1) = 5 = (7^2-1)/4-7 generated by A165349(1)=7.
a(2) = 19 = (11^2-1)/4-11 generated by A165349(2)=11.

Mathematica

Select[Table[(p^2 - 1)/4 - p, {p, Prime[Range[200]]}], PrimeQ] (* Vincenzo Librandi, Oct 12 2012 *)

Prog

(Magma) [a: p in PrimesInInterval(5, 700) | IsPrime(a) where a is (p^2 - 1) div 4 - p ]; // Vincenzo Librandi, Oct 12 2012

Crossrefs

Cf. A165349.

Sequence in context: A115103 A241043 A045457 * A138242 A163076 A122729

Adjacent sequences: A165554 A165555 A165556 * A165558 A165559 A165560

Keyword

nonn,easy

Author

Vincenzo Librandi, Sep 22 2009

Extensions

Entries checked by R. J. Mathar, Sep 26 2009

Status

approved