Sequence 5,1,5,1,5,1 General term formula How to calculate?

Sequence 5,1,5,1,5,1 General term formula How to calculate?

It's 3 + 2, 3-2, 3 + 2, 3-2
That's 3 + (+ 2), 3 + (- 2), 3 + (+ 2), 3 + (- 2)
That is, 3 + 2 * (+ 1), 3 + 2 * (- 1), 3 + 2 * (+ 1), 3 + 2 * (- 1)
That is 3 + 2 * (- 1) ^ (n + 1)
So you can understand?

General term formula of sequence: 1 2 3 5 8

The general formula is: [(1 + √ 5) ^ n - (1 - √ 5) ^ n] / √ 5

Find the rule 10,20,23,46,49,98101 () ()

10,20,23,46,49,98,101(202)(205)
The second is the first multiplied by two,
The third is the second plus three