Question

Find the missing geometric means in this sequence 1_,_,_,256

Answer 1

you could do this one easily enough by experiment. Suppose the constant is 2:

1, 2, 4, 8, 256 oops, too small, what's the next number that is a factor of 256?
not 3, let's try 4
1, 4, 16, hmm, might be worth investigating :-)