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2009 UNCO Math Contest II Problems/Problem 10

Revision as of 21:14, 19 October 2014 by Timneh (talk | contribs) (moved 2009 UNC Math Contest II Problems/Problem 10 to 2009 UNCO Math Contest II Problems/Problem 10: disambiguation of University of Northern Colorado with University of North Carolina)

Problem

Let $S=\left \{1,2,3,\ldots ,n\right \}$. Determine the number of subsets $A$ of $S$ such that $A$ contains at least two elements and such that no two elements of $A$ differ by $1$ when

(a) $n=10$

(b) $n=20$

(c) generalize for any $n$.


Solution

See also

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