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 A272296 #22 Jun 13 2017 14:33:33 %S A272296 3,11,25,341,1827,2581,4475,11157,41141,64721 %N A272296 Numbers n such that 5^n-4^(n-1) is prime. %C A272296 a(11) > 10^5. %e A272296 3 is a member since 5^3 - 4^2 = 125 - 16 = 109 which is a prime number. %t A272296 Select[Range[0, 100000], PrimeQ[5^# - 4^(# - 1)] &] %o A272296 (PARI) is(n)=ispseudoprime(5^n-4^(n-1)) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A272296 Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884, A272345. %K A272296 nonn,more %O A272296 1,1 %A A272296 _Robert Price_, Apr 27 2016