OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Power Tower.
Wikipedia, Tetration.
EXAMPLE
-1.7296376776755434144759943668608340411378592485876...
MATHEMATICA
f[x_] := -ProductLog[-Log[x]]/Log[x]; RealDigits[Derivative[4][f][1/2], 10, 120][[1]] (* Amiram Eldar, May 23 2023 *)
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Alois P. Heinz, Oct 19 2016
STATUS
approved