OFFSET
1,1
COMMENTS
Primes of the form k+(k^2-1)/8, where k >0 are prime or composite, are the superset 13, 19, 43, 53, 89, 103 etc.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Table[p + (p^2 - 1)/8, {p, Prime[Range[200]]}], PrimeQ] (* Vincenzo Librandi, Oct 12 2012 *)
PROG
(Magma) [a: p in PrimesInInterval(3, 1200) | IsPrime(a) where a is p + (p^2 - 1) div 8 ]; // Vincenzo Librandi, Oct 12 2012
(PARI) forprime(p=3, 1e4, if(isprime(t=p^2>>3+p), print1(t", "))) \\ Charles R Greathouse IV, May 15 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Sep 16 2009
EXTENSIONS
More terms from R. J. Mathar, Sep 21 2009
STATUS
approved