A sequence satisfies an=4an−1−4an−2a_n = 4a_{n-1} - 4a_{n-2}an=4an−1−4an−2 with a0=1,a1=4a_0 = 1, a_1 = 4a0=1,a1=4. What is the closed form ana_nan?
an=2n+n2na_n = 2^n + n2^nan=2n+n2n
an=(1+n)2na_n = (1+n)2^nan=(1+n)2n
an=2n+2n+1a_n = 2^n + 2^{n+1}an=2n+2n+1
an=n2na_n = n2^nan=n2n