[seqfan] Re: Need help with notation: sums of subset products

[Neil Sloane]

Speaking as a mathematician: the empty product (which is 1 by convention)
must
always be included.

(Otherwise the numbers will be ugly)

Best regards
Neil

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com


On Sat, Mar 28, 2015 at 2:38 PM, Bob Selcoe <rselcoe at entouchonline.net>
wrote:

> Hi Seqfans,
>
> I was wondering if OEIS-style notation exists for this concept: the sum Z
> of the products of all combinations of numbers in set S.  Alternatively
> stated, the sum Z of all nonempty non-proper subset products in set S.
>
> For example, S = {3,4,5};  Z = 3 + 4 + 5 + 3*4 + 3*5 + 4*5 + 3*4*5 = 119.
>
> I would like to include this concept in some entries as formulas rather
> than as comments, so notation would be helpful.
>
> Thanks in advance,
> Bob Selcoe
>
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