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 A246497 #14 Sep 06 2014 00:24:49 %S A246497 3,7,23,47,283,719,1439,2879,34549,138197,1266767,14619833,36449279, %T A246497 377982107,1432349099 %N A246497 Smallest k such that 9^^n is not congruent to 9^^(n-1) mod k, where 9^^n denotes the power tower 9^9^...^9 (in which 9 appears n times). %C A246497 For general remarks regarding sequences of this type, see A246491. %C A246497 This particular sequence shares all known terms with A082449. they might be identical. %o A246497 (Sage, cython) Use linked source from A246491 with this command: find_k_values(9,1,1) %Y A246497 Cf. A082449, A027763, A246491, A246492, A246493, A246494, A246495, A246496. %K A246497 nonn,more %O A246497 1,1 %A A246497 _Wayne VanWeerthuizen_, Aug 27 2014