for loop in paralel and series resistors

how to make for loop to comput paralel and series resistors this file ask for type of connection and use

1/R=1/R1+1/R2+...1/Rn for paralel

and use R=R1+R2+...Rn for series

also ask for nomber of n

Answer 1

[Walter Roberson]

 sum(R)

 1./sum(1./R))

[leyth alnjdawi]

i got it , thank you