A165353 Primes p such that p+(p^2-1)/8 is a prime number.

7, 17, 23, 31, 41, 71, 73, 79, 103, 113, 127, 151, 191, 233, 257, 281, 311, 337, 367, 383, 409, 433, 463, 487, 569, 577, 593, 601, 607, 647, 809, 887, 911, 953, 977, 1039, 1049, 1087, 1097, 1153, 1193, 1201, 1223, 1279, 1297, 1321, 1361, 1399, 1433, 1481, 1487

Offset: 1

Author

Vincenzo Librandi, Sep 16 2009

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A165352, A165354.

Programs

Magma

[n: n in [3..1500] |IsPrime(n) and IsPrime(n+(n^2-1) div 8)]; // Vincenzo Librandi, Sep 01 2012

Mathematica

Select[Prime[Range[250]], PrimeQ[# + (#^2 - 1)/8] &] (* Vincenzo Librandi, Sep 01 2012 *)

Formula

a(n)+(a(n)^2-1)/8 = A165352(n).

Extensions

More terms from R. J. Mathar, Sep 21 2009