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 A238501 #20 Mar 05 2014 03:51:07 %S A238501 7,11,19,31,43,47,107,127,131,151,163,167,179,191,211,223,263,283,347, %T A238501 367,443,487,491,523,547,587,643,659,751,827,839,911,1039,1051,1087, %U A238501 1103,1123,1163,1171,1223,1259,1283,1291,1327,1427,1439,1447,1487,1523,1543 %N A238501 Primes p for which x! + (p-1)!/x!==0 (mod p) has only three solutions 1<=x<=p-2. %C A238501 All terms are of the form 4*k+3. %C A238501 Using Wilson's theorem, for every p>3, p==3(mod 4) we have, at least, 3 solutions in [1,p-2] of x! + (p-1)!/x!==0 (mod p): x = 1, x = (p-1)/2, x = p-2. %F A238501 a(n) is prime(k(n)) for which A238444(k(n)) = 3. %t A238501 kmax = 400; Select[Select[4*Range[kmax]+3, PrimeQ], (r = Range[#-2]; Count[r!+(#-1)!/r!, k_ /; Divisible[k, #]] == 3)&] (* _Jean-François Alcover_, Mar 05 2014 *) %Y A238501 Cf. A238444, A238460. %K A238501 nonn %O A238501 1,1 %A A238501 _Vladimir Shevelev_, Feb 27 2014 %E A238501 More terms from _Peter J. C. Moses_, Feb 27 2014