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 A140669 #14 Apr 11 2025 16:47:51
%S A140669 1,2,3,6,10,16,105,119,1906,7917
%N A140669 Numbers k such that (k+1)^(k+1) - k^k is prime.
%C A140669 Terms found with PrimeForm. Primes corresponding to 16, 105 and 119 certified with Primo. 7917 corresponds to a 30870-digit probable prime.
%C A140669 a(11) > 20000. - _Michael S. Branicky_, Apr 11 2025
%H A140669 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IntegerSequencePrimes.html">Integer Sequence Primes</a>
%H A140669 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerDifferencePrime.html">Power Difference Prime</a>
%e A140669 17^17 - 16^16 = 808793517812627212561, which is prime, so 16 is a term.
%t A140669 Select[Table[n,{n,8000}],PrimeQ[(#+1)^(#+1)-#^#]&] (* _Vladimir Joseph Stephan Orlovsky_, Mar 03 2011 *)
%Y A140669 Cf. A134985. Equals A072164 - 1.
%K A140669 nonn,hard,more
%O A140669 1,2
%A A140669 _Rick L. Shepherd_, May 21 2008