Given the sequence a0=1,a1=1,a2=3,a3=7,a4=17,a5=41a_0 = 1, a_1 = 1, a_2 = 3, a_3 = 7, a_4 = 17, a_5 = 41a0=1,a1=1,a2=3,a3=7,a4=17,a5=41, which recurrence generates it?
an=an−1+2an−2a_n = a_{n-1} + 2a_{n-2}an=an−1+2an−2
an=2an−1+an−2a_n = 2a_{n-1} + a_{n-2}an=2an−1+an−2
an=an−1+an−2+1a_n = a_{n-1} + a_{n-2} + 1an=an−1+an−2+1
an=2an−1−an−2a_n = 2a_{n-1} - a_{n-2}an=2an−1−an−2