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 A191715 #18 Sep 08 2022 08:45:57
%S A191715 1,133,54871,1253659,31438345,863585785,25867844011,840625753991,
%T A191715 29488048443085,1111334648458165,44804977347486175,
%U A191715 1924820469011714611,87800711122303545361,4238935318038328143857,11582179256389013503203871,652184749150919163867112021
%N A191715 Nonprime numbers of the form n*(n-1)^n - (n-1)*n^(n-1) + 1.
%C A191715 If n=3, then 3*2^3-2*3^2+1=7 is prime, so 7 is not in this sequence. If n=5, then 5*4^5-4*5^4+1=2621 is prime.
%H A191715 Charles R Greathouse IV, <a href="/A191715/b191715.txt">Table of n, a(n) for n = 1..377</a>
%t A191715 Union[Select[Table[n(n-1)^n-(n-1)n^(n-1)+1,{n,30}],!PrimeQ[#]&]] (* _Harvey P. Dale_, Jun 19 2011 *)
%o A191715 (Magma) [ a: n in [2..40] | not IsPrime(a) where a is n*(n-1)^n-(n-1)*n^(n-1)+1 ]; // _Vincenzo Librandi_, Jun 13 2011
%o A191715 (PARI) for(n=1,1e3,if(!ispseudoprime(k=n*(n-1)^n-(n-1)*n^(n-1)+1),print1(k", ")))
%Y A191715 Cf. A191409, A191699.
%K A191715 nonn
%O A191715 1,2
%A A191715 _Juri-Stepan Gerasimov_, Jun 12 2011