>>10832227It (sort of) represents growth/reproduction patterns.
Let's say you have 1 couple of young rabbits. Each month a couple of young rabbits becomes adult, and each already adult couple reproduces and a new young couple is born.
First month: 1 young couple (1)
Second month: 1 new adult couple (1)
Third month: 1 already adult + 1 young (2)
Fourth month: 1 already adult + 1 new adult + 1 young (3)
Fifth month: 2 already adult + 1 new adult + 2 young (5)
Sixth month: 3 already adult + 2 new adult + 3 young (8)
Etc.