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 A128347 #11 Nov 01 2018 21:27:49
%S A128347 5,41,149,229,263,739,3457,20269,98221
%N A128347 Numbers k such that (11^k - 5^k)/6 is prime.
%C A128347 All terms are primes.
%C A128347 a(10) > 10^5. - _Robert Price_, Jan 24 2013
%t A128347 k=11; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n,1,100}]
%o A128347 (PARI) is(n)=isprime((11^n-5^n)/6) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A128347 Cf. A062572, A128344, A128345, A128346, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.
%K A128347 hard,more,nonn
%O A128347 1,1
%A A128347 _Alexander Adamchuk_, Feb 27 2007
%E A128347 a(7)-a(9) from _Robert Price_, Jan 24 2013