两个数列的连环递推,我们称之为“双连环递推”,其一般特征是:两个数列的通项由它们的首项和两个相互联系、相互制约、相互依存的递推关系联合限制给出.双连环递推数列问题是近几年数学高考和竞赛命题的一个新热点,对于求其通项公式或前n项和等问题,往往需要将这两个递推关系式 The serial recursion of two series, which we call “bicontinuous recursion,” is generally characterized by the fact that the general term for two series consists of their first and two recursive relationships that are interrelated, constrained and interdependent Joint constraints given double serial recurrence sequence is a new hot spot in mathematics college entrance examination and competition proposition in recent years, for solving its general formula or the first n items and other issues, often need to be two recurrence relations