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- From: Greg Cox <glcox AT pobox.com>
- To: "Internetworkers: http://www.ibiblio.org/internetworkers/" <internetworkers AT lists.ibiblio.org>
- Subject: Re: [internetworkers] Math Problem
- Date: Fri, 25 Feb 2005 22:07:11 -0500 (EST)
> -- the number of unique combinations of N
> characters up to a sequence of N characters. for example, for 3 the
> answer is 39:
> 3 + 3^2 + 3^3 = 3 + 9 + 27 = 39
> because the unique combinations are A, B, C, AA, ...CC, AAA, ...CCC
X characters, strings of max N length, A = answer.
A = X + X^2 + X^3 + .... + X^(N-1) + X^N
XA = X^2 + X^3 + .... + X^(N-1) + X^N + X^(N+1)
XA - A = X^(N+1) - X
A(X-1) = X^(N+1) - X
A = (X^(N+1) - X) / (X-1)
Or, in your example of X=3, N=3:
A = (3^4 - 3) / 2 = (81 - 3) / 2 = 78/2 = 39
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[internetworkers] Math Problem,
Alan MacHett, 02/25/2005
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Re: [internetworkers] Math Problem,
John Broome, 02/25/2005
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Re: [internetworkers] Math Problem,
Alan MacHett, 02/25/2005
- Re: [internetworkers] Math Problem, Ian Meyer, 02/25/2005
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Re: [internetworkers] Math Problem,
Alan MacHett, 02/25/2005
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Re: [internetworkers] Math Problem,
Greg Cox, 02/25/2005
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Re: [internetworkers] Math Problem,
Alan MacHett, 02/25/2005
- Re: [internetworkers] Math Problem, Greg Cox, 02/25/2005
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Re: [internetworkers] Math Problem,
Alan MacHett, 02/25/2005
- <Possible follow-up(s)>
- Re: [internetworkers] Math Problem, DonBartholf, 02/25/2005
- Re: [internetworkers] Math Problem, DonBartholf, 02/26/2005
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Re: [internetworkers] Math Problem,
John Broome, 02/25/2005
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