Italian Number Theorist 1175–1240

Leonardo Pisano Fibonacci (c. 1175–c. 1240) is considered by many to be the greatest number theorist of the Middle Ages. The following sequence

Leonardo Pisano Fibonacci is credited with introducing the Hindu-Arabic numbering system to Western Europe, but his fame is more often associated with the development of the Fibonacci sequence of numbers.

1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144,
233, 377, 610, 987, 1597, 2584, 4181, …

defined by F₁ = 1, F₂ = 1, and for n ≥ 3, F_n = F_n–1 + F_n–2 is called the Fibonacci sequence in his honor. The Fibonacci sequence evolved from the following problem in Fibonacci's book Liber abbaci.

A certain man put a pair of rabbits in a place surrounded by a wall. How many pairs of rabbits can be produced from that pair in a year if it is supposed that every month each pair begets a new pair which from the second month on becomes productive?

The answer is F₁₂ = 377.

It...