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Re: Product/Sums

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43011] Re: Product/Sums
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Fri, 8 Aug 2003 00:26:25 -0400 (EDT)
  • Organization: The University of Western Australia
  • References: <bgsne4$np6$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <bgsne4$np6$1 at smc.vnet.net>,
 Blimbaum Jerry DLPC <BlimbaumJE at ncsc.navy.mil> wrote:

> Sum[ k1=1 to q] Sum[k2=k1 to q] Sum[k3=k2 to q] (k1*k2*k3)
> 
> is there a way to write this as ...Product[Sum] ?

No, because it is _not_ a product of Sums. However, you can do what you 
want as follows:

  Subscript[k, 0] = 0;

  f[n_] := Sum[Evaluate[Product[Subscript[k, i], {i, 1, n}]], 
    Evaluate[Sequence @@ Table[
      {Subscript[k, i], Subscript[k, i - 1], q}, {i, n}]]]

  f[3]

Cheers,
Paul

-- 
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