Make sure Navigator (or Communicator) has Javascript enabled in your Preferences:

in Edit, Preferences, Advanced, check the box marked

- Select a
**series**Fibonacci(i) or Lucas(i) or Rabbit(i). - Type in a whole number value for i (which can be negative for Fibonacci or Lucas) in the
*From i=*box. - If you want to find all the values in a certain range, type a value in the
*To i=*box also. Leave this blank if you just want a single value of a series. -
- Select the
*Exact*- the calculator will find Fibonacci(i), Lucas(i) for i into the thousands. This may take up to a minute or more depending on your computer. Also, if i is too large, the browser may quit unexpectedly! Sorry - I cannot predict or prevent this! 'i' values up to i=2000 should be OK and Fib(2000) has more than 400 digits.
*Approximate*- Immediate result. The length of the answer decreases as i gets larger, but the index i itself may have up to digits!

**precision**of the computation: Exact or Approximate. (Ignored for*Rabbit(i)*and*Initial digits*.) -
- Select an
*Show series*- outputs the Fib or Lucas series for i in the range.
*Initial digits*- Benford's Law relates to the distribution of the initial digits of Fibonacci and Lucas numbers. (The precision buttons are irrelevant.)
*Amaze me!*- Generates a correct, random expression involving two n
^{th}-roots whose sum is 1, as mentioned on The Lucas numbers page. *Clear all*- clears all values and the output area.

**action**:

In Edit Menu - Preferences - Advanced, check the box marked 'JavaScript'.