%I #9 Jan 19 2019 22:18:25
%S 0,0,0,5,7,7,11,13,13,17,19,19,23,23,23,29,31,31,31,37,37,41,43,43,47,
%T 47,47,53,53,53,59,61,61,61,67,67,71,73,73,73,79,79,83,83,83,89,89,89,
%U 79,97,97,101,103,103,107,109,109,113,113,113,109,113,113,109,127,127
%N Greatest odd prime q < 2*n such that p < q and p prime and p = 2*n - q or 0 if no such prime exists.
%C q + p = 2*n and p*q = ((q+p)/2)^2 - ((q-p)/2)^2 = n^2 - ((q-p)/2)^2.
%C Essentially the same as A020482. - _R. J. Mathar_, Oct 24 2009
%H Pierre CAMI, <a href="/A159482/b159482.txt">Table of n, a(n) for n = 1..55000</a>
%K nonn
%O 1,4
%A _Pierre CAMI_, Apr 14 2009