%I #19 Feb 06 2021 22:00:48
%S 11,20,24,27,32,35,37,38,68,74,78,79,82,96,98,101,103,122,137,149,161,
%T 188,209,218,239,249,258,276,293,321,325,333,363,365,372,433,445,449,
%U 499,535,567,568,580,588,594,595,622,644,656,663,666,682,688,693,721,742,754,756,760,796,814,845
%N Numbers k such that A228553(k) is prime.
%H Robert Israel, <a href="/A339307/b339307.txt">Table of n, a(n) for n = 1..5000</a>
%e a(3) = 24 is in the sequence because A228553(24) = 1987 is prime.
%p f:= proc(n)
%p local S;
%p S:= select(t -> isprime(t) and isprime(2*n-t), [seq(i,i=3..n,2)]);
%p add(t*(2*n-t),t=S)
%p end proc:
%p f(2):= 4:
%p select(isprime@f, [$1..1000]);
%Y Cf. A228553, A339309.
%K nonn
%O 1,1
%A _J. M. Bergot_ and _Robert Israel_, Nov 29 2020
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