Capturing the rabbit formula in the form
of a Smalltalk method, you have the following definition for `rabbits`

:

Integer method definition • instance rabbits (self = 0 or: [self = 1]) ifTrue: [^ 1] ifFalse: [^ (self - 1) rabbits + (self - 2) rabbits] Workspace Transcript show: 'After month 1, there is ' ; show: 1 rabbits printString; cr; show: 'After month 2, there are ' ; show: 2 rabbits printString; cr; show: 'After month 3, there are ' ; show: 3 rabbits printString; cr; show: 'After month 4, there are ' ; show: 4 rabbits printString; cr; show: 'After month 5, there are ' ; show: 5 rabbits printString; cr; show: 'After month 24, there are ' ; show: 24 rabbits printString; cr Transcript After month 1, there is 1 After month 2, there are 2 After month 3, there are 3 After month 4, there are 5 After month 5, there are 8 After month 24, there are 75025

Evidently, at the end of 2 years, your book sales will be extremely healthy if those sales grow like rabbits.