[seqfan] Re: Numbers not sums of perfect powers

Benoît Jubin benoit.jubin at gmail.com
Thu Apr 15 03:37:14 CEST 2010


On Wed, Apr 14, 2010 at 12:22 PM,  <franktaw at netscape.net> wrote:
> 1 is not the sum of squares-minus-1.
> 8 is the sum of squares-minus-1; so is 16.

Of course, I completely messed up with this one: the full sequence is indeed
1,2,4,5,7,10,13
(as Richard Mathar also pointed out).

It is already in the OEIS, but with a different, less natural definition:
A123120 Numbers k>0 such that m+k is not the sum of m nonzero squares
for any m>5.
Should I propose to change the definition?

Also, the sequence for cubes is already in the OEIS: A078129.  This
leaves three new sequences to submit.  And I'm still interested in
finiteness for the general case (k^th powers).

Thanks,
Benoit

>
> Franklin T. Adams-Watters
>
> -----Original Message-----
> From: Benoît Jubin <benoit.jubin at gmail.com>
>
> ...
>
> Numbers which are not the sum of squares-minus-1
> 2,4,5,7,8,10,13,16
>
> ...
>
>
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