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%I #4 Jul 30 2020 16:02:08
%S 4,8,12,21,27,38,43,53,69,79,97,110,117,129,147,168,172,199,212,220,
%T 240,257,275,303,324,333,347,354,365,418,435,455,468,504,514,538,565,
%U 579,602,621,634,672,682,699,708,754,816,830,838,852,869,882,924,939,966
%N Average of p(n) and p(p(n)), where p(k) is the k-th prime.
%e a(4)=12 because p(4)=7 and p(7)=17.
%p a:=n->(ithprime(n)+ithprime(ithprime(n)))/2: seq(a(n),n=2..70);
%t Table[Mean[{Prime[n],Prime[Prime[n]]}],{n,2,60}] (* _Harvey P. Dale_, Jul 30 2020 *)
%Y Cf. A128234.
%K nonn
%O 2,1
%A _Emeric Deutsch_, Feb 20 2007
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