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

zak seidov zakseidov at yahoo.com
Thu Dec 25 22:47:18 CET 2008

```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/

```