Help! Will give out brainliest

Answer:
aₙ = 63 * (1/3)ⁿ
Step-by-step explanation:
In the sequence 63, 21, 7,... each term is divided by 3 to get the next term
Therefore, this is a geometric series where r (the common ratio) is 1/3.
The first term in the series is 63, so that is our a₀.
The general form for a geometric series is a₀ * rⁿ
Therefore, the formula for aₙ is
aₙ = 63 * (1/3)ⁿ
I hope this helps!