Which recursive step defines an=n2a_n = n^2an=n2?
an=an−1+2n−1a_n = a_{n-1} + 2n - 1an=an−1+2n−1
an=an−1+na_n = a_{n-1} + nan=an−1+n
an=an−1+2a_n = a_{n-1} + 2an=an−1+2
an=an−1+n2a_n = a_{n-1} + n^2an=an−1+n2