Recursionmedium
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A particle on a one-dimensional line moves 1 unit to the right with probability p=2/3p = 2/3 and 1 unit to the left with probability 1p=1/31-p = 1/3. Let PnP_n be the probability that the particle eventually reaches 0 starting from position n0n \geq 0. This satisfies the recurrence Pn=23Pn+1+13Pn1P_n = \frac{2}{3} P_{n+1} + \frac{1}{3} P_{n-1} with boundary conditions P0=1P_0 = 1 and limnPn=0\lim_{n \to \infty} P_n = 0. Find the value of P2P_2.