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 A100603 #21 May 29 2025 13:39:26
%S A100603 1,2,4,67,212,1615,2570
%N A100603 Numbers k such that (prime(k)-1)! + prime(k)^4 is prime.
%C A100603 k = {1, 2, 4, 67} yields primes p(k) = {2, 3, 7, 331}. There are no more such k up to k=100. Computed in collaboration with _Ray Chandler_.
%C A100603 Terms a(5) and greater are only probable primes. - _Iain Fox_, Mar 05 2018
%F A100603 Numbers k such that (prime(k)-1)! + prime(k)^4 is prime, where prime(k) is the k-th prime.
%e A100603 a(3) = 4 because (prime(4)-1)! + prime(4)^4 = (7-1)! + 7^4 = 720 + 2401 = 3121 is the 3rd prime of this form.
%t A100603 lst={};Do[p=Prime[n];If[PrimeQ[(p-1)!+p^4], AppendTo[lst, n]], {n, 10^2}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 08 2008 *)
%o A100603 (PARI) is(k) = my(p=prime(k)); ispseudoprime((p-1)! + p^4) \\ _Iain Fox_, Mar 05 2018
%Y A100603 Cf. A100858.
%K A100603 nonn,more
%O A100603 1,2
%A A100603 _Jonathan Vos Post_, Nov 30 2004
%E A100603 a(5) from _Iain Fox_, Mar 05 2018
%E A100603 a(6) from _Iain Fox_, Mar 11 2018
%E A100603 a(7) from _Michael S. Branicky_, May 29 2025