- #1

oscaralive

- 5

- 0

anyone knows how to compute the following serie?

\prod_{i=1}^{a}(a-i+1)^(a-i+1)

Many thanks in advance!

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- Thread starter oscaralive
- Start date

- #1

oscaralive

- 5

- 0

anyone knows how to compute the following serie?

\prod_{i=1}^{a}(a-i+1)^(a-i+1)

Many thanks in advance!

- #2

tiny-tim

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(try using the X

isn't that just 1

why not leave it as it is?

(or you could write it as (a!)

- #3

oscaralive

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Thanks

- #4

tiny-tim

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well, the log would be ∑nlogn … does that help?

- #5

oscaralive

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In fact, I come from the log serie...

[tex]\sum_{i=1}^{a}(a-i+1)log(a-i+1)[/tex]

[tex]\sum_{i=1}^{a}log((a-i+1)^{(a-i+1)})[/tex]

[tex]log(\prod_{i=1}^{a}{(a-i+1)}^{(a-i+1)})[/tex]

which now has been transformed to the product...

thanks,

[tex]\sum_{i=1}^{a}(a-i+1)log(a-i+1)[/tex]

[tex]\sum_{i=1}^{a}log((a-i+1)^{(a-i+1)})[/tex]

[tex]log(\prod_{i=1}^{a}{(a-i+1)}^{(a-i+1)})[/tex]

which now has been transformed to the product...

thanks,

Last edited:

- #6

tiny-tim

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i was wondering whether it would be close to ∫ xlogx dx

- #7

oscaralive

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I'm stuck here :(

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