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MathGroup Archive 2005

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A list of numbers without "73"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63005] A list of numbers without "73"
  • From: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>
  • Date: Sat, 10 Dec 2005 06:03:40 -0500 (EST)
  • Organization: Balliol College
  • Reply-to: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>
  • Sender: owner-wri-mathgroup at wolfram.com

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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