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%I #10 Oct 03 2016 12:36:31
%S 1,1,1,1,3,4,10,16,43,101,340,911,2544,7224,22616,65376,187754,545743,
%T 1653966,4832057,14027794
%N Number of equivalence classes of words in F_2, modulo all automorphisms of F_2, whose minimal words have length n.
%C F_2 is the free group on two generators.
%H Bobbe Cooper and Eric Rowland, <a href="http://arxiv.org/abs/0909.0561">Growing words in the free group on two generators</a>, Illinois Journal of Mathematics 55 (2011) 417-426.
%H Bobbe Cooper and Eric Rowland, <a href="https://arxiv.org/abs/1307.8216">Classification of automorphic conjugacy classes in the free group on two generators</a>, Algorithmic Problems of Group Theory, Their Complexity, and Applications to Cryptography, edited by Delaram Kahrobaei and Vladimir Shpilrain, Contemporary Mathematics 633 (2015) 13-40.
%Y A224074 is the number of root classes.
%K nonn,hard
%O 0,5
%A _Eric Rowland_, Mar 30 2013