recursive formulas

• 递推公式

recursive formulas的用法和样例：

例句

1. There is a recursive formula for the number of spanning trees in a graph.
   对于一个图的生成树的棵数，存在一个递推公式。
2. Some recursion formulae of Bessel functions are derived from such practice problems as well.
   并从该实际问题出发，推导出了一类贝塞尔函数的递推公式。