THank you for your suggestion, Mindscape.
what is "zeq" ? I googled and did not find this word.
Where shall I go back to see how parallel and series will produce smth similar??
I tried to apply Kirchhoff eqns, but i1+i2=i3 ... and V1+V2+V3+V4 = 0... so I have n unknown and n-1 equations...