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(GDR 3) Find the number of permutations a_1, \cdots, a_n of the set \{1, 2, . . ., n\} such that |a_i - a_{i+1}| \neq 1 for all i = 1, 2, . . ., n - 1. Find a recurrence formula and evaluate the number of such permutations for n \le 6.

Slični zadaci

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