[seqfan] Re: Partitioning the sequence (?)

[Leroy Quet]

If I understand your question (and I may not), then n(L) is easy.

The number of partitions of (a(1),a(2),...a(L)), where the a's maintain their order, is simply 2^(L-1).
(The divisions between the a's are each either "on" or "off".)

Don't know about the Mathematica.

Thanks,
Leroy Quet



--- On Sun, 12/21/08, zak seidov <zakseidov at yahoo.com> wrote:

> From: zak seidov <zakseidov at yahoo.com>
> Subject: [seqfan]  Partitioning the sequence (?)
> To: "seqfaneu" <seqfan at seqfan.eu>
> Date: Sunday, December 21, 2008, 8:38 PM
> Dear SeqFans,
> 
> I need to part the sequence a,b,c,d...(of length L)
> in all, n, possible ways:
> 
> a,b,c,d
> a,b,cd
> a,bc,d
> ab,c,d
> ab,cd
> a,bcd
> abc,d
> abcd
> 
> in this case L=4 and n=8 (modulo my errs).
> 
> My (humble) Qs:
> what is the function n(L) (guess that this is known one...)
> how to code this in Mathematica/PARI/Maple (in order of
> decreasing preference)
> 
> thx, zak
>  
> 
> 
> 
>       
> 
> 
> _______________________________________________
> 
> Seqfan Mailing list - http://list.seqfan.eu/