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 A375620 #13 Oct 18 2024 18:29:48 %S A375620 2,43,1723,2971,3257,12263,38933 %N A375620 Numbers k such that (20^k - 3^k)/17 is prime. %C A375620 All terms must be prime. %C A375620 a(8) > 10^5. %H A375620 OEIS Wiki, <a href="https://oeis.org/wiki/Primes_of_the_form_(a%5En%2Bb%5En)/(a%2Bb)_and_(a%5En-b%5En)/(a-b)">Primes of the form (a^n+b^n)/(a+b) and (a^n-b^n)/(a-b)</a> %e A375620 a(1) = 2 corresponds to the prime number 23. %o A375620 (PARI) is(k) = ispseudoprime((20^k - 3^k)/17) %Y A375620 Cf. A028491, A057468, A128032, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032. %K A375620 hard,more,nonn %O A375620 1,1 %A A375620 _William Dean_, Aug 21 2024