This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A339307 #19 Feb 06 2021 22:00:48 %S A339307 11,20,24,27,32,35,37,38,68,74,78,79,82,96,98,101,103,122,137,149,161, %T A339307 188,209,218,239,249,258,276,293,321,325,333,363,365,372,433,445,449, %U A339307 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 A339307 Numbers k such that A228553(k) is prime. %H A339307 Robert Israel, <a href="/A339307/b339307.txt">Table of n, a(n) for n = 1..5000</a> %e A339307 a(3) = 24 is in the sequence because A228553(24) = 1987 is prime. %p A339307 f:= proc(n) %p A339307 local S; %p A339307 S:= select(t -> isprime(t) and isprime(2*n-t), [seq(i,i=3..n,2)]); %p A339307 add(t*(2*n-t),t=S) %p A339307 end proc: %p A339307 f(2):= 4: %p A339307 select(isprime@f, [$1..1000]); %Y A339307 Cf. A228553, A339309. %K A339307 nonn %O A339307 1,1 %A A339307 _J. M. Bergot_ and _Robert Israel_, Nov 29 2020