OFFSET
1,1
COMMENTS
Usually the greatest p with p,q both prime, p+q = 2m, is equal to the largest prime <= 2m-2, but not always. These are the exceptions.
Almost all natural numbers are in the sequence so the above comment is misleading in general, and only fitting for small numbers. - Jens Kruse Andersen, Jul 13 2014
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
MATHEMATICA
a2[n_] := {p, q} /. {ToRules @ Reduce[p+q == 2*n, {p, q}, Primes]} // Max; a8[n_] := Max[FactorInteger[(2*n)!/n!^2]]; Select[Range[500], a2[#] != a8[#-1]&] (* Jean-François Alcover, Dec 19 2013 *)
PROG
(PARI) for(m=2, 1000, p=precprime(2*m-2); if(!isprime(2*m-p), print1(m", "))) \\ Jens Kruse Andersen, Jul 12 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Harry J. Smith, Nov 20 2007
STATUS
approved