Recurrence Relationshard
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The recurrence an=2an12an2a_n = 2a_{n-1} - 2a_{n-2} has characteristic roots r=1±ir = 1 \pm i. In polar form, r=2e±iπ/4r = \sqrt{2} e^{\pm i\pi/4}. The general solution is an=2n[Acos(nπ/4)+Bsin(nπ/4)]a_n = \sqrt{2}^n [A\cos(n\pi/4) + B\sin(n\pi/4)].

Given a0=1a_0 = 1 and a1=1a_1 = 1, what is a2a_2?