# [seqfan] Re: A/B*C deprecated

Neil Sloane njasloane at gmail.com
Wed Jan 1 16:18:32 CET 2020

```> How about A*C/B?
> So like 1 + x/2 + x^2/4 + x^3/8 + x^4/16?

This is fine, as is 1 + 3*x/2 + 7*x^2/4 + 15*x^3/8 + 31*x^4/16

On Wed, Jan 1, 2020 at 9:46 AM David Corneth <davidacorneth at gmail.com>
wrote:

> So like 1 + x/2 + x^2/4 + x^3/8 + x^4/16?
>
>
> On Sat, Dec 28, 2019 at 2:07 PM Neil Sloane <njasloane at gmail.com> wrote:
>
> > Dear SeqFans / Editors
> > Generations of mathematicians like myself studied from books like
> > Chrystal's classic "Algebra" (1886, 7th ed still in print from Chelsea),
> > where A/B*C means A/(B*C):
> > Here is an example picked at random:
> > Show that Sum_{1..oo} 1/n (4n^2-1)^2 = 3/2 - 2 log 2.
> >
> > On the other hand computer scientists often interpret A/B*C as (A/B)*C,
> > perhaps influenced by Maple etc.,  where one sees
> > 1 + 1/2*x + 1/4*x^2 + 1/8*x^3 + 1/16*x^4 + ... (ugh!),
> >
> > To avoid this ambiguity, in the OEIS  please never write A/B*C, always
> > write either (A/B)*C or A/(B*C).
> >
> > E.g. either
> > 1 + (1/2)*x + (1/4)*x^2 + (1/8)*x^3 + (1/16)*x^4 + ...  or
> > 1 + 1/(2*x) + 1/(4*x^2) + 1/(8*x^3) + 1/(16*x^4) + ...
> > depending on whether you want x to be very small or very large.
> >
> > --
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>

```