[seqfan] Re: A new sequence

Robert Munafo mrob27 at gmail.com
Tue Feb 5 20:50:21 CET 2013


Sorry Max, it looks like I was writing my reply while you wrote yours (-:

Anyway, you answered my question, and also explained why Guy had his
polynomials "backwards" (with the highest power of the variable first)

On 2/5/13, Maximilian Hasler <maximilian.hasler at gmail.com> wrote:
>>[...]
> Here, a script which appends n values to
> the r initial values  of a lin.rec. of order r,
> already helps:
>
> (PARI)
> {linrec(c,a,n=10)=for(k=1,n,a=concat(a,-vecextract(a,Str(-#c,".."))*c~));a}
>
> linrec([1,-40,206,-40],[1,0,1,48])
>
> [...]

Recurrence relations (or iterative formulas, or recursive definitions,
as I call them), very straightforward.

So I guess we just need to know which of the 1000 or so are recurrence
relations, and of those which sets of initial terms and of
coefficients would fit into Richard Guy's request.

I suspect the more interesting ones Guy wants are divisibility
sequences but do not have such a simple iterative formula.

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