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 A272366 #7 Jun 13 2017 14:33:32 %S A272366 7,25,29,55,75,243,345,635,899,2025,2105,2295,5057,5155,5209,11115, %T A272366 81743,97615 %N A272366 Numbers n such that 5^n-4^(n+1) is prime. %C A272366 a(19) > 10^5. %e A272366 7 is a member since 5^7 - 4^8 = 78125 - 65536 = 12589 which is a prime number. %t A272366 Select[Range[0, 100000], PrimeQ[5^# - 4^(# + 1)] &] %o A272366 (PARI) is(n)=ispseudoprime(5^n-4^(n+1)) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A272366 Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884. %K A272366 nonn,more %O A272366 1,1 %A A272366 _Robert Price_, Apr 27 2016