Which recurrence relations produce the sequence 1,2,4,8,16,...1, 2, 4, 8, 16, ...1,2,4,8,16,... for n≥1n \geq 1n≥1? (Select all)
an=2an−1a_n = 2a_{n-1}an=2an−1 with a1=1a_1 = 1a1=1
an=an−1+an−1a_n = a_{n-1} + a_{n-1}an=an−1+an−1 with a1=1a_1 = 1a1=1
an=2n−1a_n = 2^{n-1}an=2n−1 (closed form)
an=2an−1a_n = 2a_{n-1}an=2an−1 with a0=1a_0 = 1a0=1