[seqfan] Re: Empirical relation for A180169: Sigma(A180162(n)), where A180162(n) is the smallest N such that sigma(N) is an nth power, or 0 if no such N can be found

Georgi Guninski guninski at guninski.com
Fri Feb 25 17:25:31 CET 2011


Hello,

unfortunately almost the entire sequence is consecutive powers of 2...
(except for the few initial terms).

On Fri, Feb 25, 2011 at 04:59:32PM +0100, Simon Plouffe wrote:
> 
> Hello,
> 
>  for A180169, I have this
> generating function :
> 
>  (-1-x+2560*x^5+93184*x^7-46592*x^6+725590016*x^12+2*x^2-1280*x^4-362795008*x^11)/(2*x-1),
> 
> 
> It has a score of 8.34 and it matches all the
> terms in the sequence.
> 
> I checked the series and the 468'th term and they do match.
> 
>  I would say that this generating functions has good chances
> to be the good one.
> 
>  My I add it to the sequence formulas ?
> 
> Best Regards,
> 
> Simon Plouffe
> 
> 
> 
> 
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> 
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