If we're going to stick to a fixed precision numbers, and we're just out to score maximum internet points, you can do it in O(1) by just computing out a table in advance, and for not much storage space since the series grows exponentially.
I mean, if we're going to screw around with the Os let's do it properly.
The javascript solution presented does everything in O(n) arithmetic operations, and the SICP way does it in O(ln(n)) arithmetic operations (actually, there are a lot of ways to do it in O(ln(n)) operations).