Need permutation help for n!/(n-r)!

chandra sekaran on Sat, 25 Jun 2016 05:51:45 +0200

Need permutation help for n!/(n-r)!

To: pari-users@pari.math.u-bordeaux.fr
Subject: Need permutation help for n!/(n-r)!
From: chandra sekaran <sekar.bc@gmail.com>
Date: Sat, 25 Jun 2016 09:21:37 +0530
Delivery-date: Sat, 25 Jun 2016 05:51:45 +0200
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numtoperm(n,k) will give k-th permutation for n!.

Any function for n!/(n-r)! available?

For n!/(n-r)!, Let n = 50 and r = 3.

If we define r as subset say [2,3,5] i want

calculate the number where [2,3,5] occur and reverse also.

Any direct function available and if not how to calculate.

Thanks

Chandrasekaran B

Follow-Ups:
- Re: Need permutation help for n!/(n-r)!
  - From: Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>