[seqfan] Re: sigma(n) < min(sigma(n-1),sigma(n+1)), n=10*m?

zak seidov zakseidov at yahoo.com
Sun Oct 10 08:43:41 CEST 2010

> From: zak seidov <zakseidov at yahoo.com>
> Subject: [seqfan] Re: sigma(n) < min(sigma(n-1),sigma(n+1)), n=10*m?
> To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
> Date: Saturday, October 9, 2010, 5:56 AM
>
> --- On Sat, 10/9/10, zak seidov <zakseidov at yahoo.com>
> wrote:
>
> > From: zak seidov <zakseidov at yahoo.com>
> > Subject: [seqfan]  sigma(n) <
> min(sigma(n-1),sigma(n+1)), n=10*m?
> > To: "seqfaneu" <seqfan at seqfan.eu>
> > Date: Saturday, October 9, 2010, 5:53 AM
> > Dear seqfans,
> >
> > What is the least n of the form n=10*m, such that
> >
> > sigma(n) < min(sigma(n-1),sigma(n+1))?
> >
> >
> > (That is, sigma(n) is the strict local minimum;
> > sigma(n) = A00203(n) )
> >
> > First let's find at least one such n and then
> > let's try to improve the limit!
> >
> Charles Greathous gave the example
>
> n=5707019657504475216700242307626915459099744204108184475974056118653623493126356870
>
> But this not the minimum for sure!
>

The strong pretendent for the minimm is
(according to Yury Volvovskiy (and me:))

10899118150512092355662334281801606571010.

Anyone may wish to beat the record?

> > Thanks,
> > Zak