A sequence is defined by an=2an−1−an−2+6na_n = 2a_{n-1} - a_{n-2} + 6nan=2an−1−an−2+6n with a0=0,a1=1a_0 = 0, a_1 = 1a0=0,a1=1. What is the closed-form expression for ana_nan?
an=n3+na_n = n^3 + nan=n3+n
an=n3+2na_n = n^3 + 2nan=n3+2n
an=2n3−na_n = 2n^3 - nan=2n3−n
an=n3−na_n = n^3 - nan=n3−n