[seqfan] Re: multiplicative set-like sequences

Richard Guy rkg at cpsc.ucalgary.ca
Wed Feb 16 17:25:56 CET 2011

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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