User blog comment:Boboris02/Boris´s sezration notation/@comment-29014792-20161001215423

[a,b] = a -> a -> ... -> a -> a with b a's

[ # ,a] = a -> a -> ... -> a -> a with [ # ] a's

[a|b|a] = [a,a,...,a,a] with b a's

Quiet easy, but the growth rate is w^2+2. I need to go faster!