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 A118305 #8 Oct 13 2024 09:50:05 %S A118305 1,2,6,16,5436,6238 %N A118305 Numbers k such that 3*k^k-1 is prime. %C A118305 Six terms found and primes proved by PrimeForm ([N+1, Brillhart-Lehmer-Selfridge]). 3*6238^6238-1 has 23674 digits. No more terms <= 8800. %C A118305 No more terms <= 25000. - _Michael S. Branicky_, Oct 13 2024 %o A118305 (PARI) is(n)=ispseudoprime(3*n^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A118305 Cf. A118306, A110931. %K A118305 hard,more,nonn %O A118305 1,2 %A A118305 _Rick L. Shepherd_, Apr 22 2006