Answer: 3720087
Step-by-step explanation:
n=term number
an=term value
terms: 7, 21, 63...
term number: 1, 2, 3, ...
7 is 1st term. 21 is 2nd term. 63 is 3rd term.
21/7=3
63/21=3
Common change in each term is multiplication by 3
Hence, the formula can be expressed in exponents.
an=3^(n-1) * 7 where n is the term number, an is the term value, and 7 is the 1st term in the sequence.
an=3^(13-1) * 7
an=3^12 * 7
an=531441 * 7
an=3720087
