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MathGroup Archive 2005

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Re: A list of numbers without "73"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63006] Re: A list of numbers without "73"
  • From: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>
  • Date: Sun, 11 Dec 2005 04:56:29 -0500 (EST)
  • Organization: Balliol College
  • References: <dnee1r$1ep$1@smc.vnet.net>
  • Reply-to: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>
  • Sender: owner-wri-mathgroup at wolfram.com

I forgot to say that S(i) is a list of positive integers with i digits.
Best,
Thomas

"Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk> schrieb im Newsbeitrag 
news:dnee1r$1ep$1 at smc.vnet.net...
> Experts,
>
> S(i) should be a list of positive integers without the substring "73".
>
> My code seems to be very inefficient. I multiply all numbers with 0 if 
> they
> contain "73", sort the new list, make the union (remove double elements) 
> and
> delete the first element. Therefore it is necessary to use an if statement
> in order not to delete the first element of the numbers 1-9. Any more
> sophisticated ideas?
>
> L := Table[k, {k, 1, 9}]
>
> S[i_] := S[i] =
> If[i == 1, L,
> Delete[Union[
> Table[k*(1 - Boole[StringMatchQ[ToString[k], "*73*"]]), {k,
> 10^(i - 1), 10^i - 1}]], 1]]
>
>
>
> Best
>
> Thomas


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