## Problem of the Day #374: Increasing Sequence Numbers
*March 27, 2012*

*Posted by Alex in : potd , trackback*

Find the number of integers satisfying the property that the concatenation of all the odd-indexed digits (the leftmost digit is index 1), starting from the leftmost digit, followed by all the even-indexed digits, starting from the rightmost even-indexed digit, forms a strictly increasing sequence.

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