# [seqfan] Re: vampire numbers: multiple-vampire numbers?

zak seidov zakseidov at yahoo.com
Thu Dec 25 23:39:44 CET 2008

```Also, 1395 is not in Eric's page
http://mathworld.wolfram.com/VampireNumber.html

Vampire numbers having two distinct pairs of fangs include

125460	=	204·615=246·510	(8)
11930170	=	1301·9170=1310·9107	(9)
12054060	=	2004·6015=2406·5010    (10)

--- On Thu, 12/25/08, Tanya Khovanova <mathoflove-seqfan at yahoo.com> wrote:

> From: Tanya Khovanova <mathoflove-seqfan at yahoo.com>
> Subject: [seqfan] Re: vampire numbers:  multiple-vampire numbers?
> To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
> Date: Thursday, December 25, 2008, 5:01 PM
> Check this sequence out:
> A014575 Vampire numbers (numbers having more than one pair
> of fangs are
> listed once for each pair).
>
> I think the definition should explicitly state if we are
> two fangs or more fangs here.
> Another confusing sequence:
>
> A014575 Vampire numbers (numbers having more than one pair
> of fangs are
> listed once for each pair).
>
> This sequence looks like vampire numbers with exactly two
> fangs in
> different way (word "one pair"), then why 1395 is
> here? I continue to
> be confused.
>
>
> --- zak seidov <zakseidov at yahoo.com> wrote:
>
> > Hello Tanya and all you SeqFans,
> >
> > 1395 is the first non-trivial double-vampire number
> > with two valid factorizations:
> > 1395=15*93=5*9*31.
> >
> > What about other non-trivial double-vampire numbers?
> >
> > I call trivial multiple-vampire numbers those ending
> with zero's:
> > 1260=6*210=21*60,
> > 13950=>{15, 930}, {93, 150}, {5, 9, 310}, {5, 31,
> 90}, {9, 31, 50}.
> >
> > Again, what about non-trivial  multiple-vampire
> numbers?
> >
> > Happy New, 2009!
> >
> > zak
> >
> >
> > --- On Thu, 12/25/08, Tanya Khovanova
> <mathoflove-seqfan at yahoo.com>
> > wrote:
> >
> > > From: Tanya Khovanova
> <mathoflove-seqfan at yahoo.com>
> > > Subject: [seqfan]  vampire numbers
> > > To: "Sequence Fanatics Discussion list"
> <seqfan at list.seqfan.eu>
> > > Date: Thursday, December 25, 2008, 2:18 PM
> > > Hello SeqFans,
> > >
> > > I just wrote an essay about problems with names
> for vampire
> > > numbers:
> > > http://blog.tanyakhovanova.com/?p=89
> > >
> > > I suggest renaming the corresponding sequences.
> For example
> > > we might
> > > want to name:
> > > A080718 Numbers n such that all the digits of the
> prime
> > > factors of n
> > > exactly match the digits of n.
> > > --- prime-fanged vampire numbers.
> > >
> > > A014575 Vampire numbers (numbers having more than
> one pair
> > > of fangs are
> > > listed once for each pair).
> > > --- double symmetrical fangs vampire numbers.
> > >
> > > A020342 Vampire numbers: n has a factorization
> using
> > > n's digits (e.g.
> > > 1395 = 31*9*5).
> > > --- we might keep the name or call them
> generalized vampire
> > > numbers.
> > >
> > > I didn't check if all the sequences I mention
> in my
> > > essay are in the
> > > OEIS. I would like to clean the naming
> conventions first,
> > > then someone
> > > can add more sequences if desired.
> > >
> > > Best, Tanya
> > >
> > >
> > >
> > > _______________________________________________
> > >
> > > Seqfan Mailing list - http://list.seqfan.eu/
> >
> >
> >
> >
> >
> > _______________________________________________
> >
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
>
>
>
> _______________________________________________
>
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```