Feigenbaum's second constant

The second Feigenbaum constant or Feigenbaum's alpha constant ,
 * $$\alpha = 2.502\,907\,875\,095\,892\,822\,283\,902\,873\,218...,$$

is the ratio between the width of a tine and the width of one of its two subtines (except the tine closest to the fold). A negative sign is applied to $α$ when the ratio between the lower subtine and the width of the tine is measured.

These numbers apply to a large class of dynamical systems (for example, dripping faucets to population growth).

A simple rational approximation is $13⁄11$ × $17⁄11$ × $37⁄27$ = $8177⁄3267$.