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 A023590 #12 Aug 08 2020 11:29:34
%S A023590 5,7,11,5,23,3,7,13,47,59,7,5,83,29,19,107,17,41,5,13,7,53,167,179,13,
%T A023590 29,23,43,73,227,17,263,11,31,23,101,7,109,67,347,359,11,383,43,79,19,
%U A023590 47,149,13,17,467,479,23,503,103,31,11,181,37,563,7,587,41,89
%N A023590 Greatest prime divisor of 2*prime(n)+1.
%H A023590 Amiram Eldar, <a href="/A023590/b023590.txt">Table of n, a(n) for n = 1..10000</a>
%F A023590 a(n) = A006530(A072055(n)). - _Amiram Eldar_, Aug 08 2020
%t A023590 Table[FactorInteger[2Prime[n]+1][[-1,1]],{n,70}] (* _Harvey P. Dale_, Jun 22 2013 *)
%o A023590 (PARI) a(n) = vecmax(factor(2*prime(n)+1)[,1]); \\ _Michel Marcus_, Aug 08 2020
%Y A023590 Cf. A006530, A072055.
%K A023590 nonn
%O A023590 1,1
%A A023590 _Clark Kimberling_