Sum of digits of 2^n equals n

zak seidov zakseidov at yahoo.com
Mon Jul 24 11:58:51 CEST 2006



--- "Max A." <maxale at gmail.com> wrote:

> On 7/23/06, Tanya Khovanova
> <tanyakh at tanyakhovanova.com> wrote:
> > I found two numbers n such that sum of digits of
> 2^n is equal to n:
> > 5 and 70.
> >
> > I can't find the corresponding sequence.
> >
> > Are there any other numbers like that?
> 
> Such numbers be equal to 5 or 16 modulo 18.
> I've performed a search for n up to 18000. No new
> terms found.
> 
> Max
> 
Up to n=20,000,
the only cases when sod(2^n) is divisible by n are
n=1,2,5,70. Zak

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