A number in the infinite sequence 1,1,2,3,5,8,13,....of which the first two terms are I and I and each succeeding term is the sum of the two immediately preceding.

怀勃那西数；黄金分割数(连续序列或级数如1、1、2、3、5、8、13、21、34、55、89、144、...，每一数均为前两数之和)。