Answer:
F(1) represents the first term of the sequence.
Explanation:
Let us suppose the sequence function

We can find the first term of the sequence by substituting n=1 in the function sequence



We can find the 2nd term of the sequence by substituting n=2 in the function sequence



We can find the 3rd term of the sequence by substituting n=3 in the function sequence



So the first three terms of the sequence is:
13, 10, 7...
As the common difference is the same.
i.e. d = 10-13 = -3, d = 7-10 = -3
Hence, it is an Arithmetic sequence.
As the first term is 13, which can be obtained by putting n=1 in the function sequence.
Therefore, from the above discussion, we can conclude that F(1) represents the first term of the sequence.