Which recurrence corresponds to the sequence 1,2,4,7,11,…1, 2, 4, 7, 11, \dots1,2,4,7,11,…?
an=an−1+na_n = a_{n-1} + nan=an−1+n
an=an−1+n−1a_n = a_{n-1} + n - 1an=an−1+n−1
an=2an−1a_n = 2a_{n-1}an=2an−1
an=an−1+1a_n = a_{n-1} + 1an=an−1+1