## Re: Primes and Runsums

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• ... OK I get it now, he said sheepishly. I find it amazing the lengths I can go to misunderstand a problem! :) Thanks Jens. Mark
Message 1 of 5 , Jun 25, 2008
--- In primenumbers@yahoogroups.com, "Jens Kruse Andersen" <jens.k.a@...> wrote:
>
> Ronald Dwyer wrote:
> >> Using a run sum calculator website, I found the numbers in the range
> >> 1 to 150 (this was arbitrary) that are the sums of exactly 2 runs.
>
> Mark Underwood wrote:
> > From a cursory glance at the numbers Ronald has provided, this seems
> > very remarkable to me.
>
> Maybe you didn't receive my post which explains it:
> The key is that a runsum can be written as a product (where one of
> the terms may be 1).
>
> > when I add two run sums together I get a number not on Ron's list:
> >
> > (2+3+4) + (6+7+8+9) = 39.
>
> Ronald meant numbers for which there are exactly two different runs
> with the same sum, for example:
> 41 = 41 (the sum of one number), and 41 = 20+21 (the sum of two numbers).
> All odd numbers have these two sums. There are more sums if and
> only if the number is composite, for example 39 = 12+13+14 = 4+5+6+7+8+9.
>
> --
> Jens Kruse Andersen
>

OK I get it now, he said sheepishly. I find it amazing the lengths I can go to misunderstand
a problem! :)

Thanks Jens.

Mark
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