[seqfan] Re: Who understands Granville numbers?

Vladimir Shevelev shevelev at bgu.ac.il
Thu Oct 28 10:12:04 CEST 2010


About A118372. It seems very plausible that every term has the form a(n)=(2^k(n)-1)2^m(n) (maybe, this is known). If so, then there are at least 3 accompanying sequences which are not in OEIS:

for 2^k(n)-1: 3 3 7 3 63 7 3 31 3 7 3 127...
for k(n):        2 2 3 2   6  3 2  5  2 3 2    8...
for m(n):       1 3 2 5   1  5 7  4  9 8 11  6...

Regards,
Vladimir

----- Original Message -----
From: Alonso Del Arte <alonso.delarte at gmail.com>
Date: Thursday, October 28, 2010 1:10
Subject: [seqfan]  Who understands Granville numbers?
To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>

> So I come across the concept of Granville numbers
> (A118372<http://www.research.att.com/~njas/sequences/A118372>)
> in Jean-Marie de Koninck's book *Those Fascinating Numbers*. But 
> the concept
> is giving me a headache. Is the definition of the set S 
> recursive (one
> having to do a complete divisor tree to figure out membership) 
> or am I
> completely misunderstanding it? I've had an easier time doing my 
> taxes.
> Al
> 
> P.S. Daniel and I have signed up for a couple of slots for 
> Sequence of the
> Day in November. Any SeqFan who hasn't yet chosen a Sequence of 
> the Day is
> invited to sign up to choose it one day in November or December.
> 
> _______________________________________________
> 
> Seqfan Mailing list - http://list.seqfan.eu/
> 

 Shevelev Vladimir‎



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