A091301 Primes of the form p*q + p - q, where p and q are distinct primes.

5, 7, 13, 17, 19, 29, 31, 37, 41, 43, 61, 67, 73, 89, 97, 103, 109, 113, 127, 137, 139, 149, 151, 157, 181, 193, 197, 199, 211, 229, 233, 241, 257, 271, 277, 281, 283, 307, 313, 317, 337, 349, 353, 373, 379, 389, 397, 401, 409, 421, 433, 449, 457, 461, 463, 487

Offset: 1

Author

Zak Seidov, Feb 21 2004

Keywords

• easy
• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Primes of the form p*q+p+q, where p and q are primes, are in A066938.

Cf. A091310.

Programs

Mathematica

nn=100;Take[Select[Union[Flatten[{First[#]*Last[#]+First[#]-Last[#], First[#]*Last[#]- First[#]+Last[#]}&/@Subsets[Prime[Range[nn]],{2}]]], PrimeQ],nn] (* Harvey P. Dale, Jul 12 2014 *)

PARI

list(lim)=my(v=List(),t);forprime(q=2,lim,forprime(p=2,(lim+q)\(q+1),if(ispseudoprime(t=p*q+p-q),listput(v,t))));vecsort(Vec(v),,8) \\ Charles R Greathouse IV, Feb 15 2011

Extensions

Definition clarified by Harvey P. Dale, Jul 12 2014