OFFSET
1,1
COMMENTS
All a(n) == 3 (mod 8), as this is necessary for p, p1 and p2 to be odd. - Robert Israel, May 11 2014
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
67 is in the sequence because 67, ceiling(67/2) + 67 = 101 and floor(101/2) + 101 = 151 are all primes.
MAPLE
N:= 10^5; # to get all entries <= N
filter:= proc(p)
local p1, p2;
if not isprime(p) then return false fi;
p1:= ceil(p/2)+p;
if not isprime(p1) then return false fi;
p2:= floor(p1/2)+p1;
isprime(p2);
end proc;
select(filter, [seq(2*i+1, i=1..floor((N-1)/2)]; # Robert Israel, May 09 2014
MATHEMATICA
lst={}; Do[p=Prime[n]; If[PrimeQ[p=Ceiling[p/2]+p], If[PrimeQ[p=Floor[p/2]+p], AppendTo[lst, Prime[n]]]], {n, 7!}]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Mar 24 2009
EXTENSIONS
Definition corrected by Robert Israel, May 09 2014
STATUS
approved