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 A277524 #12 Feb 16 2025 08:33:37 %S A277524 1,9,0,1,7,1,3,9,0,7,5,2,6,0,0,3,9,8,6,2,6,2,6,3,9,9,8,2,1,2,4,6,9,9, %T A277524 5,1,4,4,4,6,4,8,8,5,7,4,5,2,4,0,5,0,5,3,1,6,2,0,0,0,9,0,0,9,1,3,5,1, %U A277524 5,9,4,3,5,4,5,0,7,5,5,4,2,9,0,3,4,9,2,6,8,4,0,1,4,2,1,2,6,0,2,6,6,8,4,7,1,6,5 %N A277524 Decimal expansion of the third derivative of the infinite power tower function x^x^x... at x = 1/2. %H A277524 Alois P. Heinz, <a href="/A277524/b277524.txt">Table of n, a(n) for n = 1..1000</a> %H A277524 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PowerTower.html">Power Tower</a>. %H A277524 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetration">Tetration</a>. %e A277524 1.901713907526003986262639982124699514446488574524050... %t A277524 f[x_] := -ProductLog[-Log[x]]/Log[x]; RealDigits[f'''[1/2], 10, 120][[1]] (* _Amiram Eldar_, May 23 2023 *) %Y A277524 Cf. A033917, A104748, A277522, A277523, A277525, A277526, A277527, A277528, A277529, A277530, A277531. %K A277524 nonn,cons %O A277524 1,2 %A A277524 _Alois P. Heinz_, Oct 19 2016