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 A277525 #12 Feb 16 2025 08:33:37 %S A277525 1,7,2,9,6,3,7,6,7,7,6,7,5,5,4,3,4,1,4,4,7,5,9,9,4,3,6,6,8,6,0,8,3,4, %T A277525 0,4,1,1,3,7,8,5,9,2,4,8,5,8,7,6,2,4,7,5,4,3,6,2,8,4,5,2,7,3,6,5,9,6, %U A277525 9,2,3,4,8,6,2,8,9,4,3,3,4,5,2,1,7,5,6,7,1,2,3,8,4,8,3,8,7,0,4,5,2,4,4,0,8,8 %N A277525 Decimal expansion of the fourth derivative of the infinite power tower function x^x^x... at x = 1/2, negated. %H A277525 Alois P. Heinz, <a href="/A277525/b277525.txt">Table of n, a(n) for n = 1..1000</a> %H A277525 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerTower.html">Power Tower</a>. %H A277525 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetration">Tetration</a>. %e A277525 -1.7296376776755434144759943668608340411378592485876... %t A277525 f[x_] := -ProductLog[-Log[x]]/Log[x]; RealDigits[Derivative[4][f][1/2], 10, 120][[1]] (* _Amiram Eldar_, May 23 2023 *) %Y A277525 Cf. A033917, A104748, A277522, A277523, A277524, A277526, A277527, A277528, A277529, A277530, A277531. %K A277525 nonn,cons %O A277525 1,2 %A A277525 _Alois P. Heinz_, Oct 19 2016