[seqfan] Re: multiplicative set-like sequences

[Charles Greathouse]

Actually, wait -- I think Richard Guy is right here.  These actually
aren't multiplicative sequences (though their indicator function would
be).  They might better be described by as some variant of
divisibility sequences.

Charles Greathouse
Analyst/Programmer
Case Western Reserve University

On Wed, Feb 16, 2011 at 11:25 AM, Richard Guy <rkg at cpsc.ucalgary.ca> wrote:
> Perhaps the more usual term for such sequences is
> ``strong divisibility sequence''   [as opposed
> to ``divisibility sequence'' which is just
> ``m|n  implies  a(m)|a(n)'']      ??    R.
>
> On Wed, 16 Feb 2011, Max Alekseyev wrote:
>
>> SeqFans,
>>
>> We have a keyword 'mult' for multiplicative sequences satisfying the
>> property:
>> a(mn)=a(m)a(n) if g.c.d.(m,n)=1
>>
>> However, besides functional sequences, we have many set-like sequences
>> defined by phrases like "Integers n such that ...".
>> The multiplicativeness property is naturally defined for such sequences as
>> mn in the the sequence if m,n are in the sequence and g.c.d.(m,n)=1
>>
>> Should such set-like sequences are also marked with the 'mult' keyword?
>> A typical candidate would be A023172.
>>
>> Regards,
>> Max
>>
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>>
>
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