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 A128449 #25 Jul 29 2024 07:16:55
%S A128449 2,10,50,7900,18494,23840,36838
%N A128449 Numbers k such that absolute value of 9^k - k^9 is prime.
%C A128449 Three larger terms 18494, 23840 and 36838 found by _Donovan Johnson_, Jul-Aug 2005.
%C A128449 From the Lifchitz link: 83024 is also a term. - _Michael S. Branicky_, Jul 29 2024
%H A128449 Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=9%5En-n%5E9&action=Search">PRP Records</a>.
%t A128449 lst={};k=9;Do[If[PrimeQ[Abs[k^n-n^k]], AppendTo[lst, n]], {n, 0, 10^4}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 10 2008 *)
%o A128449 (PARI) is(n)=isprime(abs(9^n-n^9)) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A128449 Cf. A072180, A109387, A117705, A117706, A128447, A128448, A128450, A128451, A122003, A128453, A128454.
%K A128449 hard,more,nonn
%O A128449 1,1
%A A128449 _Alexander Adamchuk_, Mar 03 2007
%E A128449 a(4)-a(6) from _Ryan Propper_, Feb 22 2008
%E A128449 a(7) from _Donovan Johnson_, Feb 26 2008