There is an infinite ladder-shaped grid of 1Ω resistors connecting adjacent nodes as follows:

What is the electrical resistance between (a) and (b)? Note: in the image, every resistor is 1Ω.

(In reply to

Solution by Bractals)

Without following the logic (Physics is a very-long-time-ago subject for me), based on the recurrence by Bractals, Q should be 1+√3 -- you get this by substituting Q for all Q(...) and solving the resulting equation.