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 A141798 #12 Feb 20 2017 14:52:51
%S A141798 0,1,5,21,261,47589,93337
%N A141798 Numbers n such that 2*23^n + 1 is prime.
%C A141798 Primes found and proved by PrimeForm. No more terms up to 20000.
%C A141798 a(6) and a(7) proved prime by the primality proving program LLR. - _Robert Price_, Jan 06 2016
%C A141798 a(8) > 2*10^5. - _Robert Price_, Jan 06 2016
%t A141798 Join[{0}, Select[Range[1, 261, 2], PrimeQ[2*23^# + 1] &]] (* _Arkadiusz Wesolowski_, Nov 06 2012 *)
%o A141798 (PARI) is(n)=ispseudoprime(2*23^n+1) \\ _Charles R Greathouse IV_, Feb 20 2017
%Y A141798 Cf. A141774, A141797, A141802, A190942, A068231.
%K A141798 hard,nonn
%O A141798 1,3
%A A141798 _Rick L. Shepherd_, Jul 05 2008
%E A141798 a(6)-a(7) from _Robert Price_, Jan 06 2016