Which cube members are not in the sequence and prove it?

2, 5, 8, 11, 14, ...

How can this be proved :confused:

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- Feb 12th 2006, 11:25 AMNatasha2, 5, 8, 11, 14... (q1)
Which cube members are not in the sequence and prove it?

2, 5, 8, 11, 14, ...

How can this be proved :confused: - Feb 13th 2006, 01:48 PMThePerfectHackerQuote:

Originally Posted by**Natasha**

$\displaystyle 3k+2=x^3$

I believe you may state that,

$\displaystyle x^3\equiv 1\mod 3$

if and only if, (there is a $\displaystyle k$ such as)

$\displaystyle 3k+2=x^3$.

Thus, all the values of $\displaystyle x$ which are

"cubic residues" which are $\displaystyle 1,4,7,10,13,...$

Maybe?