where the minimum is taken over all permutations. This result is best possible since in any permutation there must be an ai such that [ai,ai+1] \geq (1+o(1))\frac{n2}{4 log n}. It is also shown that there is an infinite permutation a1,a2,... of the positive integers such that
for all i. Some results are also obtained for the greatest common divisor. See also following review.
Reviewer: I.Anderson
Classif.: * 11B05 Topology etc. of sets of numbers
11A05 Multiplicative structure of the integers
11B75 Combinatorial number theory
05A05 Combinatorial choice problems
Keywords: permutations; density of sums; least common multiple; greatest common divisor
Citations: Zbl.518.10064
© European Mathematical Society & FIZ Karlsruhe & Springer-Verlag