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 A252661 #11 Sep 08 2022 08:46:10 %S A252661 2,7,9,111,129,133,361 %N A252661 Numbers m such that 8^m - m is a semiprime. %C A252661 a(8) >= 369. - _Hugo Pfoertner_, Aug 03 2019 %H A252661 factordb.com, <a href="http://factordb.com/index.php?query=8%5E369-369">Status of 8^369-369</a>. %e A252661 2 is in this sequence because 8^2-2 = 2*31 is semiprime. %e A252661 9 is in this sequence because 8^9-9 = 23*5835553 and these two factors are prime. %t A252661 Select[Range[70],PrimeOmega[8^# - #]==2 &] %o A252661 (Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [m: m in [1..70] | IsSemiprime(s) where s is 8^m-m]; %Y A252661 Cf. similar sequences listed in A252656. %K A252661 nonn,more,hard %O A252661 1,1 %A A252661 _Vincenzo Librandi_, Dec 21 2014 %E A252661 a(4)-a(7) from _Hugo Pfoertner_, Aug 03 2019