Difference between revisions of "2016 UNCO Math Contest II Problems/Problem 8"

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Revision as of 01:38, 20 May 2017

Problem

Tree


Each circle in this tree diagram is to be assigned a value, chosen from a set $S$, in such a way that along every pathway down the tree, the assigned values never increase. That is, $A \ge B, A \ge C, C \ge D, C \ge E$, and $A, B, C, D, E \in S$. (It is permissible for a value in $S$ to appear more than once.)

(a) How many ways can the tree be so numbered, using only values chosen from the set $S = \{1, . . . , 6\}$?

(b) Generalize to the case in which $S = \{1, . . . , n\}$. Find a formula for the number of ways the tree can be numbered.

For maximal credit, express your answer in closed form as an explicit algebraic expression in $n$.

Solution

See also

2016 UNCO Math Contest II (ProblemsAnswer KeyResources)
Preceded by
Problem 7
Followed by
Problem 9
1 2 3 4 5 6 7 8 9 10
All UNCO Math Contest Problems and Solutions