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 A257769 #13 Jan 11 2020 15:57:46 %S A257769 0,1,4,65536,7625597484987 %N A257769 Perfect hyper-5 powers: a^^^b, where b <> 1. %C A257769 a^^b (a to the hyper-4 power b) is the right associative power tower a^a^...^a^a of height b. %C A257769 a^^^b (a to the hyper-5 power b) is the right associative hyper-4 power tower a^^a^^...^^a^^a of height b. a^^^-1 = 0, a^^^0 = 1; %C A257769 We exclude b=1 because otherwise all natural numbers would be in the sequence. %e A257769 Numbers satisfying the properties stated above: %e A257769 3^^^2 = 3^^3 = 3^3^3 = 3^27 = 7625597484987; %e A257769 2^^^3 = 2^^2^^2 = 2^^4 = 2^2^2^2 = 2^2^4 = 2^16 = 65536; %e A257769 1^^^4 = 1^^1^^1^^1 = 1. %Y A257769 Cf. A001597, A257309. %K A257769 nonn,bref %O A257769 1,3 %A A257769 _Natan Arie Consigli_, May 07 2015