here ,
make those ends where curren t simply flows be free den
if pointing end of each circle is free
thus
in infinite sereis
one resistance doesnt effect
therefore
if x is eq resistance
n r is resistace of one side den
in parralel
1/r 1=1/(x)+1/(r)
r1=rx/(r+x)
now in series
r2=rx/(r+x)+r=2rx+r 2/(r+x)
finally taking parralel for final side n thus d eq resistance
1/x=(r+x)/2rx+r 2+1/r=3x+2r/(2rx+r 2)
thus solving
x=r/
3 hope its correct