Difference between revisions of "2012 AMC 10B Problems/Problem 22"
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Revision as of 00:54, 24 December 2012
Problem 22
Let (, , ... ) be a list of the first 10 positive integers such that for each 2 10 either or or both appear somewhere before in the list. How many such lists are there?
$\textbf{(A)}\ \120\qquad\textbf{(B)}\512\qquad\textbf{(C)}\ \1024\qquad\textbf{(D)}\ 181,440\qquad\textbf{(E)}\ \362,880$ (Error compiling LaTeX. Unknown error_msg)