The original commenter uses n to indicate which value in the sequence is being computed. They then say that there is a O(log(n)) algorithm (that is, it grows with the logarithm of the index) that can find the nth Fibonacci number. The n in O(log(n)) is still referring to that same index in the sequence, it has not changed its meaning. I do not know how else to explain this to you. At this point I can only presume that you are confused about the fundamentals of algorithm analysis or you're a troll.