A115058 Primes p such that 3p+2 is not prime.

2, 11, 31, 41, 47, 53, 61, 67, 71, 73, 101, 107, 109, 113, 131, 137, 151, 157, 179, 181, 191, 193, 211, 223, 229, 241, 251, 263, 271, 277, 281, 283, 307, 311, 331, 347, 359, 373, 379, 389, 401, 421, 431, 443, 449, 461, 463, 467, 487, 491, 509, 521, 541, 547

Offset

1,1

Comments

Complement of A023208 in the prime numbers A000040.

Primes p that are also the largest prime factor of p(p^2-1)(3p+2)/24.

References

Number Theory, George E. Andrews 1971, Dover Publications New York, p 4.

Links

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

Example

p=11, p(p^2-1)(3p+2)/24 = 1925 = 5*5*7*11.

Mathematica

a={}; Do[p=Prime[n]; If[ !PrimeQ[3*p+2], AppendTo[a, p]], {n, 8^2}]; a - Vladimir Joseph Stephan Orlovsky, Apr 29 2008
Select[Prime[Range[100]], ! PrimeQ[3 # + 2]&] (* Vincenzo Librandi, Apr 17 2013 *)

Prog

(Magma) [p: p in PrimesUpTo(600) | not IsPrime(3*p + 2)]; // Vincenzo Librandi, Apr 17 2013

Crossrefs

Sequence in context: A094005 A190154 A187830 * A158295 A213898 A085041

Adjacent sequences: A115055 A115056 A115057 * A115059 A115060 A115061

Keyword

easy,nonn

Author

Cino Hilliard, Feb 28 2006

Extensions

Edited by Max Alekseyev, Feb 06 2010

Status

approved