5

Part of 2004 Iran MO (3rd Round)

Problems(1)

easy permutation

Source: iran2004(com exam)

assume that k,n are two positive integer

k\leq n

count the number of permutation

\{\ 1,\dots ,n\}\

1\leq i,j\leq k

and any positive integer m we have

f^m(i)\neq j

f^m

meas iterarte function,)

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