# Generator
def fibonacci(n):
# input: [f(i-2), f(i-1), countdown]
def fib: (.[0] + .[1]) as $sum
| if .[2] == 0 then $sum
else $sum, ([ .[1], $sum, .[2] - 1 ] | fib)
end;
[-1, 1, n] | fib;