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 A087038 #22 Apr 01 2018 20:27:50 %S A087038 2,3,2,3,444 %N A087038 Smallest integer x > 1 such that x^x + n is prime, or 0 if no such x exists. %C A087038 The sequence with the unknown terms indicated by ?: 2, 3, 2, 3, 444, ?, 2, ?, 2, 3, ?, 5, 2, 3, 2, 3, ?, 19, 2, 3, 4, 19, 6, ?, 2, 3, 2, 15, 30, 7, 6, 3, 2, 3, 6, ?, 2, 5, 2, 3, ... %C A087038 The unknown terms a(6), a(8), a(11), a(17), a(24), a(36) are > 6000. %C A087038 It is conjectured that such x always exists. - _Dean Hickerson_ %C A087038 We can show that for all n=(6k-1)^3, k > 0, there is no such x, which disproves the conjecture. See the main entry A087037 for more details. - _Farideh Firoozbakht_ and _M. F. Hasler_, Nov 27 2009 %H A087038 OpenPFGW Project, <a href="http://www.primeform.net/openpfgw/">Primality Tester</a> %e A087038 a(4)=3 because 3^3 + 4 = 27 + 4 = 31 is prime. %Y A087038 Cf. A000312 (n^n), A087037 (x^x+n is prime, x>0). %K A087038 nonn,more %O A087038 1,1 %A A087038 _Hugo Pfoertner_, Jul 31 2003 %E A087038 Name edited by _Altug Alkan_, Apr 01 2018