# Math

posted by Pia

What type of sequence is this. 2/3, 1/3, 2/9, 1/6
Please give me the general formula.

1. Steve

check for a common difference or ratio between terms.
difference means arithmetic
ratio means geometric

2. Reiny

1/3 - 2/3 = -1/3
2/9 - 1/3 = -1/9 , so it is NOT arithmetic

1/3 ÷ 2/3 = 1/2
2/9 ÷ 1/3 = 2/3 , so it is NOT geometric

let's change them to ...
2/3, 1/3, 2/9, 1/6 , ....
= 2/3, 2/6, 2/9, 2/12, ....
= 2/(3*1) , 2/(3*2) , 2/(3*3), 2/(3*4), ....
mmmmhhhh?

3. Pia

Well i guess it is a harmonic sequence. Thanks a lot!

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