OFFSET
0,2
COMMENTS
The value can be calculated to an accuracy of at least 4.8×10^183230 decimal digits by calculating log(...log(7^...^1)...).
LINKS
Proof that the series converges (StackExchange, 10/09/2012)
FORMULA
-log(...log(n^(n-1)^...^1)...)(n nested log)
EXAMPLE
-0.0613312423000835123439855996950060450612102645287...
MATHEMATICA
p[n_] := HoldForm[n]^(p[n - 1]); p[1] := 1; rules = {Log[x_ y_] :> Log[x] + Log[y], Log[x_^k_] :> k Log[x]}; lnn[x_, n_] := Log[lnn[x, n - 1]]; lnn[x_, 0] := x; RealDigits[ReleaseHold[lnn[p[7], 7] //. rules], 10, 100, 0]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Benedikt Otten, Nov 03 2012
STATUS
approved