159955

I noticed that when the input value is less than or equal to zero, there is an undefined output. From there, I thought logarithms must be involved in the function. I increased one of the bottom numbers to 2, leaving the others equal to 1. When I saw the output was 1, I realised that the log must be to base 2, as log to base anything of 1 is 0. I then used different input values and figured that the function was log to base 2 of the lower two numbers added together.