A pattern or sequence formula

If you have this pattern 0,1,1,2,3,5,8,13,12,7,10,8,9,... and those are the outputs of a function where F(0) = 0, and F(1) = 1 and so on, what is the function? I figured out that adding the previous two digits make the next digit when I call my function F(10) the answer should be 10 but in my case, I got 55.

Any help would be greatly appreciated, and thanks in advance!