(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The sequence is 1 1 1 1 5 5 5 5 1 1 1 1

I need to find the formula for the sequence.

2. Relevant equations

3. The attempt at a solution

I had a previous problem that was similar. It was a sequence of 1 5 1 5 1 5. I managed to get it with the formula of 3+2(-1)^{n}.

I did a little research through my notes/book and I found an explanation. It said I could set n equal to a fraction to get it to alternate numbers for different lengths. It was implying that (-1)^{n/2}would give me 2 repeating of the number from the equation, (-1)^{n/4}would give me 4 repeating, etc.

I understand the concept, at least, I think I do, but when I punch it into my calculator, (-1)^{n/any#}gives me an error. I know (-1)^{n/#}is the same as the # root of the number, and the root of -1 is an imaginary number.

Maybe I misunderstood something in the notes. Anyone point me in the right direction? Thanks.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Repeating sequence

**Physics Forums | Science Articles, Homework Help, Discussion**