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 A216826 #13 Mar 14 2020 18:53:21
%S A216826 2,3,7,43,31,47059,3109,1729101023519
%N A216826 Largest prime factor of the n-th primary pseudoperfect number A054377(n).
%C A216826 See A054377 for comments, references, and links.
%e A216826 42 = 2*3*7 is the third primary pseudoperfect number, so a(3) = 7.
%t A216826 A054377 = Cases[Import["https://oeis.org/A054377/b054377.txt", "Table"], {_, _}][[All, 2]];
%t A216826 Max /@ FactorInteger[A054377] (* _Robert Price_, Mar 14 2020 *)
%Y A216826 Cf. A054377, A216825, A236433.
%K A216826 nonn,hard,more
%O A216826 1,1
%A A216826 _Jonathan Sondow_, Sep 20 2012