Re: sum of recursive fn: solving for n
- To: mathgroup at smc.vnet.net
- Subject: [mg22146] Re: sum of recursive fn: solving for n
- From: Brian Higgins <bghiggins at ucdavis.edu>
- Date: Wed, 16 Feb 2000 02:35:10 -0500 (EST)
- References: <888afd$c7p@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Fiona, Here is a brut force approach:
f[x_Integer] := f[x - 1]*2
f[0] = 2
solver[nmax_Integer, RHS_Integer] :=
Do[If[Sum[f[x], {x, 1, n}] == RHS, Break[Print["n=" <> ToString[n]]]],
{n, 1, nmax}]
solver[10, 252]
n=6
Cheers, Brian
In article <888afd$c7p at smc.vnet.net>,
fiona <reply at newsgroup.please> wrote:
>
> what am i doing wrong here?
>
> f[x_] := (f[x-1])*2
> f[1] =2
> Solve[Sum[f[x], {x, 1,n}] ==62, n]
>
> tia,
> fiona
>
>
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