A recurrence relation an=an−1+an−2a_n = a_{n-1} + a_{n-2}an=an−1+an−2 with a0=0,a1=1a_0 = 0, a_1 = 1a0=0,a1=1. What is the closed form?
an=ϕn−ψn5a_n = \frac{\phi^n - \psi^n}{\sqrt{5}}an=5ϕn−ψn
an=ϕn+ψn5a_n = \frac{\phi^n + \psi^n}{\sqrt{5}}an=5ϕn+ψn
an=ϕn+ψna_n = \phi^n + \psi^nan=ϕn+ψn
an=ϕn−ψn2a_n = \frac{\phi^n - \psi^n}{2}an=2ϕn−ψn