The golden thread, part 5: Leonardo of Pisa

This is a long shot for inclusion in the golden thread:

In Liber abacci of 1202, Leonardo of Pisa defined the "Fibonacci series" in the context of a problem on population dynamics:

{1, 2, 3, 5, 8, 13, 21, ...}
which is continued by adding two consecutive terms to get the next term.

This is connected to the golden thread by the fact that the ratio of consecutive terms approaches PHI in the limit. However, we do not know if he knew this.

Ralph H. Abraham, 13 May 1996.