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 A231901 #19 Jun 13 2022 03:02:06
%S A231901 1,2,4,4,6,6,11,9,11,10,20,12,15,15,16,16,18,18,23,21,22,22,40,25,27,
%T A231901 31,28,28,37,30,42,38,34,36,42,36,110,39,43,40,42,42,56,46,50,46,55,
%U A231901 65,51,51,53,52,55,55,73,58,58,58,60,60,63,63,177,68,70,66,82,72
%N A231901 Least k > n such that k!/n! + 1 is a prime, or 0 if no such k exists.
%H A231901 Vincenzo Librandi, <a href="/A231901/b231901.txt">Table of n, a(n) for n = 0..1000</a>
%t A231901 Table[k = n + 1; While[! PrimeQ[k!/n! + 1], k++]; k, {n, 100}] (* _T. D. Noe_, Nov 18 2013 *)
%o A231901 (PARI) a(n) = {my(m = n+1); while(! isprime(m!/n! +1), m++); m;} \\ _Michel Marcus_, Mar 07 2014; corrected Jun 13 2022
%Y A231901 Cf. A002981, A035093, A057217, A075757, A075758, A231549.
%K A231901 nonn
%O A231901 0,2
%A A231901 _Alex Ratushnyak_, Nov 15 2013