Func Fibonacci(n) = if n<0 then -(-1)^n*Fibonacci(-n) else if n<2 then n else
Array fib[n+1];
fib[1] := 0;
fib[2] := 1;
for i = 2, n do
fib[i+1]:=fib[i]+fib[i-1]
od;
Return(fib[n+1]);
fi;
.