有一对兔子，从出生后第3个月起每个月都生一对兔子，小兔子长到第四个月后每个月又生一对兔子，假如兔子都不死，问每个月的兔子总数为多少？

-----程序分析： 兔子的规律为数列1,1,2,3,5,8,13,21-A pair of rabbits from the first 3 months after the birth of every month from birth to a rabbit, bunny long to four months gave birth to one pair of rabbits every month, if the rabbit is not dead, and asked the rabbit month How many total?----- Program analysis: number of rabbits out 1,1,2,3,5,8,13,21 .... the law