What is the closed form of an=an−1+2n−1a_n = a_{n-1} + 2n - 1an=an−1+2n−1 with a0=0a_0=0a0=0?
an=n2a_n = n^2an=n2
an=n2−1a_n = n^2-1an=n2−1
an=2n2a_n = 2n^2an=2n2
an=n(n+1)a_n = n(n+1)an=n(n+1)