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 A191513 #22 Apr 13 2025 14:58:08 %S A191513 3,5,10,11,18,127,286,560,1025 %N A191513 Numbers k such that k*(k-1)^k - 1 is prime. %C A191513 a(10) > 20000. - _Michael S. Branicky_, Apr 13 2025 %e A191513 a(1)=3 because 3*2^3-1=23 is prime, a(2)=5 because 5*4^5-1=5119 is prime, a(3)=10 because 10*9^10-1=34867844009 is prime, a(4)=11 because 11*10^11-1=1099999999999 is prime. %p A191513 isA191513 := proc(n) n*(n-1)^n-1 ; isprime(%) ; end proc: %p A191513 for n from 1 do if isA191513(n) then print(n); end if; end do: # _R. J. Mathar_, Jun 30 2011 %o A191513 (Magma) [n: n in [1..600]| IsPrime(n*(n-1)^n-1)]; // _Vincenzo Librandi_, Jun 13 2011 %o A191513 (PARI) for(n=1,1e4,if(ispseudoprime(n*(n-1)^n-1),print1(n", "))) \\ _Charles R Greathouse IV_, Jun 14 2011 %Y A191513 Cf. A191699, A191717. %K A191513 nonn,hard,more %O A191513 1,1 %A A191513 _Juri-Stepan Gerasimov_, Jun 13 2011 %E A191513 Corrected and extended by _Vincenzo Librandi_ and _Charles R Greathouse IV_, Jun 14 2011