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 A062623 #18 Jul 04 2021 09:00:41 %S A062623 2,19,769,773,4507,26183 %N A062623 Numbers k such that 57^k - 56^k is prime. %C A062623 Terms greater than 1000 often correspond only to strong pseudoprimes. [Clarified by _M. F. Hasler_, Sep 15 2013] %C A062623 a(7) > 10^5. - _Robert Price_, Dec 06 2012 %o A062623 (PARI) is(n)=ispseudoprime(57^n-56^n) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A062623 Cf. A000043, A057468, A059801, A059802, A062572-A062666. %K A062623 nonn,hard %O A062623 1,1 %A A062623 _Mike Oakes_, May 18 2001, May 19 2001 %E A062623 a(6) from _Robert Price_, Dec 06 2012