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 A073443 #22 Nov 13 2024 14:11:01 %S A073443 3,4,10,12,346 %N A073443 Numbers k such that k! - k - 1 is prime. %C A073443 Clearly n <> 2 (mod 3). For n>3, n!-n, n!-n+1, ..., n!-3, n!-2 is a sequence of n-1 consecutive composite numbers. Additional terms are greater than 2000. %C A073443 a(5) > 7500. - _Michael S. Branicky_, Mar 04 2021 %C A073443 a(5) > 24000. - _Michael S. Branicky_, Nov 13 2024 %t A073443 Select[Range[3, 346], PrimeQ[#! - # - 1] &] (* _Arkadiusz Wesolowski_, Jan 04 2012 *) %o A073443 (PARI) for(n=3,2000,if(isprime(n!-n-1),print1(n,","))) %o A073443 (Python) %o A073443 from math import factorial %o A073443 from sympy import isprime %o A073443 def ok(n): return isprime(factorial(n) - n - 1) %o A073443 print([m for m in range(3, 500) if ok(m)]) # _Michael S. Branicky_, Mar 04 2021 %Y A073443 Cf. A073444 (corresponding primes), A002982 (n!-1 is prime), A073308 (n!+n+1 is prime). %K A073443 nonn,hard,more %O A073443 1,1 %A A073443 _Rick L. Shepherd_, Jul 31 2002 %E A073443 Offset corrected by _Arkadiusz Wesolowski_, Jan 04 2012