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 A256519 #16 Apr 04 2015 19:14:55
%S A256519 25,121,169,437,551,667,721,1037,1159,1273,1349,1403,1541,1769,1943,
%T A256519 2209,2329,2363,2419,3071,3713,4087,5041,5111,7313,8357,8479,9017,
%U A256519 11357,11983,12673,16117,16343,19043,19099,19879
%N A256519 Composites c for which an integer 1 < k < c exists such that (c-k)! == -1 (mod c).
%C A256519 The 1 < k part of the condition in the definition is implied by Wilson's theorem.
%H A256519 Charles R Greathouse IV, <a href="/A256519/b256519.txt">Table of n, a(n) for n = 1..719</a>
%e A256519 c = 25 satisfies the congruence with k = 21, since ((25-21)!+1) mod 25 = 0, so 25 is a term of the sequence.
%o A256519 (PARI) forcomposite(c=1, , for(k=1, c-1, if(Mod((c-k)!, c)==-1, print1(c, ", "); break({1}))))
%o A256519 (PARI) is(n)=if(isprime(n), return(0)); my(m=Mod(6,n)); for(k=4,n,m*=k; if(m==-1, return(1));if(gcd(m,n)!=1,return(0))) \\ _Charles R Greathouse IV_, Apr 02 2015
%K A256519 nonn
%O A256519 1,1
%A A256519 _Felix Fröhlich_, Apr 01 2015
%E A256519 a(25)-a(36) from _Charles R Greathouse IV_, Apr 02 2015