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 A269544 #30 Jun 13 2017 14:32:34 %S A269544 2,40,58,60,130,144,752,7462,18162,69028,187272,268178,270410,497284, %T A269544 713304,722600,1005254 %N A269544 Numbers n such that 7*8^n + 1 is prime. %C A269544 a(n) is even because 7*8^(2*k+1) + 1 is divisible by 3. %F A269544 a(n) = A032353(n)/3 where this is an integer. %t A269544 Select[Range[0, 200000,2], PrimeQ[7*8^# + 1] &] %o A269544 (PARI) is(n)=ispseudoprime(7*8^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A269544 Cf. A056799, A245241, A268061. %K A269544 nonn,hard,more %O A269544 1,1 %A A269544 _Robert Price_, Feb 29 2016