Final answer:
The formula to find the nth term of the given sequence is a₁ = 3; an = an-1.21.
Step-by-step explanation:
The formula that can be used to find the nth term of the given sequence 3, 21, 147 is a₁ = 3; an = an-1.21. This means that the first term (a₁) is 3, and each subsequent term (an) is equal to the previous term multiplied by 21.
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