If A(x)=11−x−x2A(x) = \frac{1}{1-x-x^2}A(x)=1−x−x21 is the generating function, what is the recurrence relation?
an=an−1+an−2a_n = a_{n-1} + a_{n-2}an=an−1+an−2
an=an−1−an−2a_n = a_{n-1} - a_{n-2}an=an−1−an−2
an=an−2+an−1a_n = a_{n-2} + a_{n-1}an=an−2+an−1
an=2an−1+an−2a_n = 2a_{n-1} + a_{n-2}an=2an−1+an−2