# Tetration Forum

You're currently viewing a stripped down version of our content. View the full version with proper formatting.
A Mathematica program to compute tetration ${^z a}$ for $1 and $\Re(z)>-2$ based on the formula with q-binomial coefficients from http://mathoverflow.net/q/259278/9550.

Increase Terms and/or WorkingPrecision option values to get more digits. Examples of values computed using this program are http://goo.gl/MLfEMC and http://goo.gl/LVRkk7.

Code:
```ClearAll[Tetration]; Options[Tetration] = {Terms -> 40, WorkingPrecision -> 100}; Tetration[_, -1, OptionsPattern[]] = 0; Tetration[a_, n_Integer /; n >= 0, OptionsPattern[]] := Power @@ Table[a, {n}]; Tetration[a_ /; 1 < a < E^(1/E), z_ /; Re[z] > -2, OptionsPattern[]] :=   With[{q = -ProductLog[-Log[a]]},   With[{limit = SequenceLimit[N[Accumulate[Table[Sum[(-1)^(n + k) q^Binomial[n - k, 2] QBinomial[z, n, q] QBinomial[n, k, q] Tetration[a, k], {k, 0, n}], {n, 0, OptionValue[Terms]}]], OptionValue[WorkingPrecision]]]},    SetPrecision[limit, 3/4 Precision[limit]]]];     (* Examples:    Tetration[Log[3], 1/2]    Tetration[Log[3], 1/2, Terms -> 50, WorkingPrecision -> 150] *)```