%I #4 Oct 13 2012 00:22:37
%S 5,8,11,18,21,31,32,35,45,59,66,69,79,92,93,95,105,119,127,141,144,
%T 153,154,168,171,179,181,195,202,218,221,228,229,231,245,255,277,279,
%U 302,304,305,315,329,331,354,357,360,363,370,381,384,389,418,431,438,444
%N Half-sums (averages) of two primes with indices that are primes with prime indices.
%C The complement is A175320 which appears to be finite.
%C Computed at the suggestion of _Jonathan Vos Post_.
%F (A038580(i) + A038580(j))/2
%Y Cf. A174681
%K easy,nonn
%O 1,1
%A _Jason Kimberley_, Apr 04 2010