For a regular m-furcating tree, the authors derive a recurrence formula of the number of its S(n)={Ki:1≤i≤n}-factor through analysing the relation among i,t and m of sub-furcating trees. Specially, m=2, the recurrence formula of a regular binary tree is as follows: At=At/22+2At/42 At/2, with initial conditions: A2=3, A4=15. |