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 A285982 #26 Apr 30 2017 22:33:00 %S A285982 1,1,2,0,3,0,0,0,5,0,6,0,0,0,8,0,9,0,0,0,11,0,0,0,0,0,14,0,15,0,0,0,0, %T A285982 0,18,0,0,0,20,0,21,0,0,0,23,0,0,0,0,0,26,0,0,0,0,0,29,0,30,0,0,0,0,0, %U A285982 33,0,0,0,35,0,36,0,0,0,0,0,39,0,0,0,41,0,0 %N A285982 a(n) = n! (mod n + 3). %C A285982 Nonzero terms are a(2 * A130290(n) - 2) = A130290(n) for n > 1. - _David A. Corneth_, Apr 30 2017 %H A285982 Robert Israel, <a href="/A285982/b285982.txt">Table of n, a(n) for n = 0..10000</a> %H A285982 Wikipedia, <a href="https://en.wikipedia.org/wiki/Wilson's_theorem">Wilson's theorem</a> %F A285982 a(n) = A000142(n) (mod n + 3). %F A285982 If n > 1 and a(n) > 0, a(n) = n/2 + 1 and n + 3 is a prime. %p A285982 seq(n! mod (n+3), n=0..100); # _Robert Israel_, Apr 30 2017 %o A285982 (PARI) a(n) = n! % (n+3); \\ _Michel Marcus_, Apr 30 2017 %Y A285982 Cf. A000142, A061006, A130290. %K A285982 nonn %O A285982 0,3 %A A285982 _Seiichi Manyama_, Apr 29 2017