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 A277526 #12 Feb 16 2025 08:33:37 %S A277526 4,9,2,8,5,9,0,7,6,3,7,5,8,5,1,0,1,7,7,6,0,3,3,5,1,7,8,7,8,9,2,8,5,7, %T A277526 1,2,5,7,9,5,7,1,4,7,8,2,5,3,8,5,0,5,4,6,8,4,6,7,2,6,6,0,0,4,7,1,2,7, %U A277526 6,2,0,4,1,6,3,9,6,2,1,2,9,2,1,9,5,9,8,8,5,3,1,4,8,7,9,3,7,9,1,6,2,6,4,3,0,5,7 %N A277526 Decimal expansion of the fifth derivative of the infinite power tower function x^x^x... at x = 1/2. %H A277526 Alois P. Heinz, <a href="/A277526/b277526.txt">Table of n, a(n) for n = 2..1001</a> %H A277526 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerTower.html">Power Tower</a>. %H A277526 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetration">Tetration</a>. %e A277526 49.2859076375851017760335178789285712579571478... %t A277526 f[x_] := -ProductLog[-Log[x]]/Log[x]; RealDigits[Derivative[5][f][1/2], 10, 120][[1]] (* _Amiram Eldar_, May 23 2023 *) %Y A277526 Cf. A033917, A104748, A277522, A277523, A277524, A277525, A277527, A277528, A277529, A277530, A277531. %K A277526 nonn,cons %O A277526 2,1 %A A277526 _Alois P. Heinz_, Oct 19 2016