[seqfan] Re: A173279 and A173280

[Robert Munafo]

On Mon, Feb 22, 2010 at 09:43, Klaus Brockhaus <klaus-brockhaus at t-online.de>
 wrote:

> ... and does it make sense to repeat the %N line (essentially) in the %F
> line?
>

No, because %F is for formulas.

For now, A173279's %F can say A(n)=A000142(A082375(n))

Or, if someone wants to create a closed-form expression for A082375(n), then
use that in A173279's %F and add it as a %F for A082375 while you're at it.

For A173280, I still don't understand what the definition is supposed to be,
so no valid %F is apparent. Maybe just take the %F line out entirely for
that sequence.

On Mon, Feb 22, 2010 at 09:43, Klaus Brockhaus
<klaus-brockhaus at t-online.de>wrote:

> ... and does it make sense to repeat the %N line (essentially) in the %F
> line?
>
> %N A173279 Triangle read by columns, factorial numbers A000142 in every
> column shifted down twice, for k>0.
> %F A173279 Triangle by columns, factorial numbers A000142 in every column
> shifted down twice, for k>0.
>
> %N A173280 Triangle by columns, factorial numbers A000142 in every column
> shifted down twice, for k>0.
> %F A173280 Triangle by columns, factorial numbers A000142 in every column
> shifted down twice, for k>0.
>
> Robert Munafo schrieb:
> > I found an error in A173279: the 8th row of the triangle (the row
> starting
> > with 5040) is duplicated.
> >
> > The description of A173279 seems wrong: given the explicit display of the
> > triangle, the sequence is clearly "by rows" not "by columns". Also, a "by
> > columns" reading of that triangle would simply be A0142 down the first
> > column and would never reach the 2nd or subsequent columns.
> >
> > Also, the description of A173280 does not seem to match the terms: it
> bears
> > the similar description to that of A173279 but does not seem to be a
> > triangle by rows or by columns. it starts out like A136580 then differs
> by
> > 0,2,2,10,18,88,...
> >
> > Perhaps Gary or someone else can provide a better explanation for
> A173280?
> >
> > I have submitted the change to remove the duplicated row in A173279 but
> am
> > unsure about the description, given how many times a nonintuitive
> > description turns out to be valid (albeit obscure) maths jargon.
>
-- 
 Robert Munafo  --  mrob.com