a pleasing notation

[Marc LeBrun]

Briefly, I've lately been writing Zb[n](x) for the polynomial in argument x 
whose coefficients are the corresponding digits of index n in base b.

It facilitates expressing many identities, including natural but 
notationally neglected concrete "numerical" operations (digit reversal, for 
instance) and overall just seems to promote a useful perspicuity.

For example, "Z2[(5*4^k-2)/3](1/tau) = 1" might form a nice commentary on 
A020989.

It also suggests many interesting generalizations.  Perhaps you too will 
like this?