find counta() per row using arrayformula()

I have this table :

https://docs.google.com/spreadsheets/d/1ICEL33X3ADz7XEH2Cmi1p6mrYT2RqPwbtBjCHWoNkoA/edit?usp=sharing

enter image description here

Basically i want to do counta() per row but using arrayformula(). The basic formula i use in A2 :

=counta(TRANSPOSE(B2:2))

Thanks