Q about LCM(1..n-1) <LCM(1..n)< LCM(1..n+1)

[zak seidov]

%I A000001
%S A000001 2,3,4,7,8,16,31,127,256
%N A000001 Numbers n such that 
lcm(1..(n-1))<lcm(1..n)<lcm(1..(n+1)).
%C A000001 Or, numbers n such that 
A003418(n-1)<A003418(n)<A003418(n+1).
Are all numbers of kind 2^m or 2^m-1?
%t A000001 ta=Table[(LCM @@ Range[n]),{n,2000}];
Do[If[ta[[i-1]]<ta[[i]]<ta[[i+1]],Print[i]],{i,2,1999}]
%Y A000001 A003418
%O A000001 1
%K A000001 ,nonn,
%A A000001 Zak Seidov (zakseidov at yahoo.com), Jan 17
2008



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