Determine Whether the Sequence Is Arithmetic $n$ Begins with 1 $$a _ { n } = - \left( \frac { 1 } { 6 } \right) ^ { n }$$

Multiple Choice

Determine whether the sequence is arithmetic. If so, find the common difference. (Assume that $n$ begins with 1.)
$$a _ { n } = - \left( \frac { 1 } { 6 } \right) ^ { n }$$

A) $- 1$
B) 6
C) $\frac { 1 } { 6 }$
D) 1
E) not arithmetic