Thanks. ]]>

*[Correction added, thanks – T.]*

First thanx for the reply, and second for the elucidation.

It was kind of obvious, but I wasn´t seeing it.

By the way I am studying your book “analysis”. I’m a portuguese student on 2ºyear of 3 on economics, on a further 2 years masters degree.

My course don’t have much mathematics, so I’m teaching myself.

I do it because I like maths, and I need a strong basis to be more analitical, quantitative, beeing more capable of study advanced technical books, and improve mind thinking.

I have good grades on mathematics now, but not really good ones. I think I’m very clever, “small genius”, but always frooze on tests. Some teachers said that I have an excellent mathematical reasoning.

On 12º my math teacher gave me 1 more value on 0-20 scale because of a probablistic problem that I solved with sequencies.

Do you have any suggestion how I should aproach tests?

With a final comment I would like to express my admiration for your work, community interaction, and the reasons why you work on mathematics.

Thanx, and good luck for everything in your life,

Regards.

On the other hand, the converse implication is always true: “ab|n” implies both “a|n” and “b|n”, regardless of how many common factors a and b have.

]]>Thanx,

Regards.

when

n=5 k=3,

1^3+2^3+3^3+4^3+5^3=225 (not divisible by 6)

in case,

i think you intended when n=(even) whole expression is divisible by n(n+1)/2

(you showed it at problem 2.6)

*[Correction added, thanks – T.]*