Which of these satisfies an=2an−1−an−2a_n = 2a_{n-1} - a_{n-2}an=2an−1−an−2?
an=na_n = nan=n
an=2na_n = 2^nan=2n
an=1a_n = 1an=1
an=n2a_n = n^2an=n2