For an=2an−1−an−2+2na_n = 2a_{n-1} - a_{n-2} + 2nan=2an−1−an−2+2n with a0=1,a1=2a_0 = 1, a_1 = 2a0=1,a1=2, find a4a_4a4.
222222
242424
262626
282828