Re: Combinations and Counting
- To: mathgroup at smc.vnet.net
- Subject: [mg118924] Re: Combinations and Counting
- From: Peter Pein <petsie at dordos.net>
- Date: Mon, 16 May 2011 03:34:21 -0400 (EDT)
- References: <iqoc0v$m8r$1@smc.vnet.net>
Am 15.05.2011 13:05, schrieb Dean Rosenthal:
> What might be the most efficient way to write a little program that counted
> combinations in the following way:
>
> 1 choose 1, 2 choose 1, 2 choose 2, 3 choose 1, 3 choose 2, 3 choose 3, 4
> choose 1, 4 choose 2, 4 choose 3 ... continuing the pattern ...
>
> So that I would be able to derive each subset in that order? Invoking
> "subsets" in the most rudimentary way *almost* gets me there, but I would
> like to see the output of this series of combinations in this special order,
> in column form, and be able to carry out my search much further.
>
> Suggestions?
>
> Thanks!
>
> DR
Hi,
if I'm not completely wrong,
NestList[(Plus @@@ Partition[Flatten[{1, #, 0}], 2, 1])&, {1}, 5]
should do the list. Replace "5" by your upper bound.
Peter