This painting is based on a problem Medieval mathematician Leonardo Pisano Bigollo, aka Fibonacci, (c. 1175 – c. 1250) brought to the West from his travels in India. He published it in his 1202 treatise Liber Abaci (Book of Abacus or Book of Calculation.) The now famous problem and a couple of published solutions to it read:
"How many pairs of rabbits will be produced in a year, beginning with a single pair, if in every month each pair bears a new pair which becomes productive from the second month on?"
To calculate the number of pairs in a month, n+1, will be Xn (notes: in this problem, rabbits never die, and all pairs produce another fertile male/female pair) plus the number of new pairs born. But new pairs are only born to pairs at least 1 month old, so there will be Xn-1 new pairs. Then, Xn+1 = Xn + Xn-1, which is the rule for generating the Fibonacci sequence/code, adds the last two to get the next. Following this, after 12 months, there will be 233 pairs of rabbits. But, in a later publication, Fibonacci states that at the end of one year there will be 377 rabbit pairs.