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ASU 459 All Soviet Union MO 1987 T_0 set consists of all (2k)!

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August 7, 2019
setnumber theorycombinatorics

Problem Statement

The T0T_0 set consists of all the numbers, representable as (2k)!,k=0,1,2,...,n,...(2k)!, k = 0, 1, 2, ... , n, .... The TmT_m set is obtained from Tm1T_{m-1} by adding all the finite sums of different numbers, that belong to Tm1T_{m-1}. Prove that there is a natural number, that doesn't belong to T1987T_{1987}.