For example:

10 terminal taxa there are 34,459,425 rooted bifurcating trees

15 taxa there are 213,458,046,676,875 rooted bifurcating trees

30 taxa there are 4 e78 trees.

(4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000)

For comparison it is estimated that there are 1 e79 atoms in the entire universe, (don’t believe me?, you count ‘em).

例如：

10个末端分类单元有34459425棵二岐分叉树

15个末端分类单元有213458046676875棵二岐分叉树

30个分类群有4的78次方棵树。

为了比较，据估计整个宇宙中有1的79次方个原子（不相信吗？，你去数一数吧）。

http://bio.slu.edu/mayden/systematics/bsc420520lect12.html

Tree Building Techniques

建树方法