User blog comment:Boboris02/Boris´s sezration notation/@comment-30118230-20161005182310/@comment-29014792-20161005213633

I have new extension:

[@(@_2)x] = [@/x]_[@/x]_... with x subscripts

[@(@_2)@] = [@(@_2)[a([@(@_2)[a([...])b]])b]]

[@(@_2*2)@] = [@(@_2+[@(@_2+...)@])@]

[@_(n-1)(@_n)x] = [@_(n-1)/x]_[@_(n-1)/x]_... with x subscripts

We could have {@,n} = @_n (suggested by Alemagno)