Find an explicit formula for the arithmetic sequence
81
,
54
,
27
,
0
,
.
.
.
81,54,27,0,...81, comma, 54, comma, 27, comma, 0, comma, point, point, point.
Note: the first term should be
a(1)
a(1)start text, a, left parenthesis, 1, right parenthesis, end text.