St.Peterburg, P7 Grade 11, 2013
Source:
April 17, 2014
combinatorics proposedcombinatorics
Problem Statement
In the language of wolves has two letters and , any finite sequence which forms a word. А word is called 'subpart' of word if Y is obtained from X by deleting some letters (for example, the word has 8 'subpart's: F, P, FF, FP, PF, FFP, FPF, FFF). Determine such that the is the greatest number of 'subpart's can have n-letter word language of wolves.
F. Petrov, V. Volkov