OFFSET
1,1
COMMENTS
All terms must necessarily be primes of form 4n+1. - Jens Kruse Andersen, Jul 15 2014
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
MAPLE
N:= 10000; # get all entries <= N
P3:= select(isprime, [seq(4*i+3, i=0..floor((N-3)/4))]):
select(isprime, [seq((P3[i]+P3[i+1])/2, i=1..nops(P3)-1)]); # Robert Israel, Jul 15 2014
PROG
(PARI)
p=[]; forstep(n=3, 5000, 4, if(isprime(n), p=concat(p, n))); p;
s=[]; for(k=1, #p-1, if(isprime(q=(p[k]+p[k+1])\2), s=concat(s, q))); s \\ Colin Barker, Jun 27 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Jun 26 2014
EXTENSIONS
One term deleted and another term inserted by Colin Barker, Jun 27 2014
STATUS
approved