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 A367003 #11 Oct 29 2024 03:40:53 %S A367003 1,7,23,7,53,383,179,89,271,3413,2503,2137,59,367,1433,41,15803,59729, %T A367003 26423,11161,1559,12611,9187523,127867,119837257,11527,2360833,43969, %U A367003 2339,32212254719,257503,616318177,260587,127873,682902239,44939,69660839431,1185617 %N A367003 a(n) is the largest prime factor of n*2^n-1. %H A367003 Amiram Eldar, <a href="/A367003/b367003.txt">Table of n, a(n) for n = 1..865</a> %F A367003 a(n) = A006530(A003261(n)). %t A367003 a[n_] := FactorInteger[n*2^n - 1][[-1, 1]]; Array[a, 40] (* _Amiram Eldar_, Oct 29 2024 *) %Y A367003 Cf. A003261, A006530, A005420, A367002, A367004, A366899. %K A367003 nonn %O A367003 1,2 %A A367003 _Sean A. Irvine_, Oct 31 2023