Hi

Well it depends by your level in maths

The characteristic polynomial is whose roots are -1, 1 and 2

-1)^n + \beta \: 1^n + \gamma \: 2^n" alt="a_n = \alpha \-1)^n + \beta \: 1^n + \gamma \: 2^n" />

, , values are found by the values of , ,

-1)^n + 6 \:\: 1^n - 2^n" alt="a_n = -2 \-1)^n + 6 \:\: 1^n - 2^n" />