%I A040018
%S A040018 1,1,3,8,46,176,955,5446
%N A040018 (Number of permutations of {1,2,...n} for which sums of adjacent numbers 
               are all distinct)/2n.
%C A040018 Essentially different ways 1,2,3,...n can be placed around a circle so 
               that sums of adjacent numbers are distinct.
%Y A040018 Cf. A091217, A006967.
%Y A040018 Sequence in context: A071533 A000240 A132103 this_sequence A019016 A063859 
               A034183
%Y A040018 Adjacent sequences: A040015 A040016 A040017 this_sequence A040019 A040020 
               A040021
%K A040018 hard,nonn
%O A040018 3,3
%A A040018 Erich Friedman (erich.friedman(AT)stetson.edu)
%E A040018 One more term from Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 25 2007