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 A217356 #20 Jun 06 2017 14:32:55 %S A217356 1,2,4,6,12,22,50,270,606,800,1704,5462,6194,9206,10306,105380 %N A217356 Numbers n such that 8^n - 5 is prime. %C A217356 All terms are equal to 1/3 of the multiples of 3 in A059608. %t A217356 Select[Range[4000], PrimeQ[8^# - 5] &] %o A217356 (PARI) is(n)=ispseudoprime(8^n-5) \\ _Charles R Greathouse IV_, Jun 06 2017 %Y A217356 Cf. A059608, A217355. %K A217356 nonn %O A217356 1,2 %A A217356 _Vincenzo Librandi_, Oct 02 2012