On the existence of sequences of co-prime pairs of integers

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    We say that a positive integer d has property (A) if for all positive integers m there is an integer x, depending on m, such that, setting n = m + d, x lies between m and n and x is co-prime to mn. We show that infinitely many even d and infinitely many odd d have property (A) and that infinitely many even d do not have property (A). We conjecture and provide supporting evidence that all odd d have property (A). Following A. R. Woods [3] we then describe conditions (Au) (for each u) asserting, for a given d, the existence of a chain of at most u + 2 integers, each co-prime to its neighbours, which start with m and increase, finishing at n = m + d. Property (A) is equivalent to condition (A1) and it is easily shown that property (Ai) implies property (Ai+1). Woods showed that for some u all d have property (Au), and we conjecture and provide supporting evidence that the least such u is 2. 1980 Mathematics subject classification (Amer. Math. Soc.) (1985 Revision): 11 A 05.

    Original languageEnglish
    Pages (from-to)84-89
    Number of pages6
    JournalJournal of the Australian Mathematical Society
    Issue number1
    Publication statusPublished - 1989

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