A165350 Primes p such that floor((p^2-1)/4)+p is not prime.

13, 23, 43, 53, 67, 71, 73, 79, 83, 97, 101, 103, 113, 137, 149, 157, 163, 167, 173, 179, 181, 193, 197, 211, 223, 233, 241, 257, 263, 269, 271, 277, 283, 293, 311, 313, 331, 349, 353, 373, 379, 383, 401, 409, 419, 421, 431, 433, 443, 457, 463, 467, 499

Offset

1,1

Links

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

Mathematica

Select[Prime[Range[2, 200]], ! PrimeQ[(#^2 - 1) / 4 + #]&] (* Vincenzo Librandi, Sep 12 2013 *)

Prog

(Magma) [p: p in PrimesUpTo(500)| not IsPrime(Floor((p^2-1)/4)+p)]; // Vincenzo Librandi, Sep 12 2013

Crossrefs

Cf. A163419, A163420.

Sequence in context: A225519 A213655 A119488 * A236418 A112394 A067227

Adjacent sequences: A165347 A165348 A165349 * A165351 A165352 A165353

Keyword

nonn,easy

Author

Vincenzo Librandi, Sep 16 2009

Extensions

Edited (but not checked) by N. J. A. Sloane, Sep 25 2009

Status

approved