In mathematics, the Fibonacci numbers or Fibonacci sequence are the numbers in the following integer sequence:or (often, in modern usage):By definition, the first two numbers in the Fibonacci sequence are either 1 and 1, or 0 and 1, depending on the chosen starting point of the sequence, and each subsequent number is the sum of the previous two.In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relationwith seed valuesorThe Fibonacci sequence is named after Italian mathematician Leonardo of Pisa, known as Fibonacci. His 1202 book Liber Abaci introduced the sequence to Western European mathematics, although the sequence had been described earlier as Virahanka numbers in Indian mathematics. By modern convention, the sequence begins either with F0=0 or with F1=1. The sequence described in Liber Abaci began with F1=1. https://en.wikipedia.org/wiki/Fibonacci_number