# A number theory problem by sudoku subbu

Number Theory Level pending

LET N BE THE SET OF NATURAL NUMBERS. SUPPOSE F:N------->N IS A FUNCTION SATISFYING THE FOLLOWING CONDITIONS (A) F(MN)=F(M)F(N) (B)F(M)<F(N)IF M<N (C)F(2)=2

THEN WHAT IS THE VALUE OF ∑_(k=1)^20▒〖F(K)〗

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