98th Kürschák Competition 1998

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1.  Can you find an infinite set of positive integers such that each pair has a common divisor (greater than 1), no integer (greater than 1) divides all members of the set, and no member of the set divides any other member?
2.  Show that there is a polynomial with integer coefficients whose values at 1, 2, ... , n are different powers of 2.
3.  For which n > 2 can we find n points in the plane, no three collinear, so that for each triangle of the points which are in the convex hull, exactly one of the points belongs to its interior.

The original problems are in Hungarian. Many thanks to Péter Dombi for the translation.

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John Scholes
jscholes@kalva.demon.co.uk
20 May 2002
Last corrected/updated 19 Apr 03