# Zag numbers

A Neighborhood of Infinity finds the power series expansion of tan(x) (somehow related to Joyce trees and Tremolo permutations) using a cute cellular-automaton-like iteration.

Here's the Python code I used to try it out:

**ETA:** ANoI's explanation

### Comments:

**None**: tan(x) actually

**2006-03-14T21:41:26Z**

If you want to evaluate the exact automaton in my post that should be `v=[1,0,1]`

. That'll fix the extraneous `1+`

.

--

Dan, aka sigfpe

**11011110**:

**2006-03-15T01:07:00Z**

I edited the post to change it from `1+tan(x)`

to `tan(x)`

by starting with `[0,1]`

instead of `[1,1]`

.