Computing Series Product: a-i+1^a-i+1

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Discussion Overview

The discussion revolves around computing the series product \(\prod_{i=1}^{a}(a-i+1)^{(a-i+1)}\). Participants explore methods to simplify or analyze this expression, particularly in the context of algorithm complexity and upper bounds.

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant inquires about the computation of the series product and seeks assistance.
  • Another participant suggests that the product could be represented in a simpler form, questioning the necessity of computation.
  • A participant mentions the need for an upper bound to define algorithm complexity, indicating that a straightforward representation is insufficient for their purposes.
  • There is a suggestion that the logarithm of the product can be expressed as a sum, specifically \(\sum_{i=1}^{a}(a-i+1)\log(a-i+1)\).
  • One participant proposes that the logarithmic series might relate to the integral \(\int x\log x \, dx\).
  • A participant expresses frustration about being stuck in their calculations.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to compute the product or its implications for algorithm complexity. Multiple approaches and perspectives are presented without resolution.

Contextual Notes

Participants reference logarithmic transformations and integral approximations, but the discussion does not clarify the assumptions or steps involved in these transformations.

Who May Find This Useful

Individuals interested in algorithm complexity, mathematical series, and logarithmic transformations may find this discussion relevant.

oscaralive
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Hi all,
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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hi oscaralive! :smile:

(try using the X2 icon just above the Reply box :wink:)

isn't that just 11223344…aa

why not leave it as it is? :confused:

(or you could write it as (a!)a over something)
 
Because I'm trying to find an upper bound to define the complexity of an algorithm...and I cannot put it that way...it would be great to find an appropriate upper bound to this product

Thanks
 
well, the log would be ∑nlogn … does that help? :smile:
 
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,
 
Last edited:
i was wondering whether it would be close to ∫ xlogx dx
 
I'm stuck here :(
 

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