The formula calculates the sum of a range of Fibonacci numbers. F(n) = F(n-1) + F(n-2), with F(0) = 0 and F(1) = 1. F(n) = F(1) + F(2) + ... + F(n-1) with F(0) = 0 and F(1) = 1.

Rules for Fibonacci Numbers\n\n Fibonacci sequence numbers follow a rule according to which, F_n = F_n-1 + F_n-2, where n > 1. The third Fibonacci number is given as F₂ = F₁ + F₀. As we know, F₀ = 0 and F₁ = 1, the value of F₂ = 0 + 1 = 1.