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 A067658 #9 Jul 20 2019 08:06:54 %S A067658 7,47,79,103,127,191,199,263,367,383,431,479,503,599,607,631,727,743, %T A067658 823,839,863,887,991,1087,1151,1319,1367,1423,1487,1511,1583,1663, %U A067658 1783,1823,1871,1951,2039,2063,2111,2143,2287,2311,2383,2423,2447,2503,2551 %N A067658 Odd integers k such that k = gcd(((k-1)/2)!+1, ((k-1)/2)^((k-1)/2)+1). %C A067658 gcd(k!+1, k^k+1)= 1 or 2k+1 with 2k+1 prime but if 2m+1 is prime 2m+1 is not necessarily in the sequence. %K A067658 nonn %O A067658 1,1 %A A067658 _Benoit Cloitre_, Feb 03 2002