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 A277530 #12 Feb 16 2025 08:33:37 %S A277530 8,4,4,6,1,7,0,8,6,7,1,0,9,3,6,1,1,9,7,5,1,5,8,2,0,7,1,1,4,9,3,8,3,2, %T A277530 2,3,9,5,4,6,1,0,0,2,1,7,3,6,6,2,7,5,5,1,8,4,4,1,7,2,9,4,8,3,6,5,8,0, %U A277530 2,4,8,4,2,5,9,8,1,7,4,6,6,3,5,1,9,8,8,5,9,6,2,2,4,9,1,5,0,1,6,9,8,4,3,5,1 %N A277530 Decimal expansion of the ninth derivative of the infinite power tower function x^x^x... at x = 1/2. %H A277530 Alois P. Heinz, <a href="/A277530/b277530.txt">Table of n, a(n) for n = 6..1005</a> %H A277530 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerTower.html">Power Tower</a>. %H A277530 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetration">Tetration</a>. %e A277530 844617.08671093611975158207114938322395461002... %t A277530 f[x_] := -ProductLog[-Log[x]]/Log[x]; RealDigits[Derivative[9][f][1/2], 10, 120][[1]] (* _Amiram Eldar_, May 23 2023 *) %Y A277530 Cf. A033917, A104748, A277522, A277523, A277524, A277525, A277526, A277527, A277528, A277529, A277531. %K A277530 nonn,cons %O A277530 6,1 %A A277530 _Alois P. Heinz_, Oct 19 2016