[Here's the formula](https://github.com/fredley/exponent/blob/master/main.js#L64 https://github.com/fredley/exponent/blob/master/main.js#L64), I came up with a

[Here's the formula](https://github.com/fredley/exponent/blob/master/main.js#L64 https://github.com/fredley/exponent/blob/master/main.js#L64), I came up with a basic exponential growth equation and tweaked it so that the speed of growth felt about right.