MathDB
E 9

Source:

May 25, 2007

Problem Statement

Four integers are marked on a circle. On each step we simultaneously replace each number by the difference between this number and next number on the circle in a given direction (that is, the numbers aa, bb, cc, dd are replaced by a−ba-b, b−cb-c, c−dc-d, d−ad-a). Is it possible after 19961996 such steps to have numbers aa, bb, cc and dd such that the numbers ∣bc−ad∣|bc-ad|, ∣ac−bd∣|ac-bd| and ∣ab−cd∣|ab-cd| are primes?
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