A224073 Number of equivalence classes of words in F_2, modulo all automorphisms of F_2, whose minimal words have length n.

1, 1, 1, 1, 3, 4, 10, 16, 43, 101, 340, 911, 2544, 7224, 22616, 65376, 187754, 545743, 1653966, 4832057, 14027794

Offset

0,5

Comments

F_2 is the free group on two generators.

Links

Table of n, a(n) for n=0..20.

Bobbe Cooper and Eric Rowland, Growing words in the free group on two generators, Illinois Journal of Mathematics 55 (2011) 417-426.

Bobbe Cooper and Eric Rowland, Classification of automorphic conjugacy classes in the free group on two generators, Algorithmic Problems of Group Theory, Their Complexity, and Applications to Cryptography, edited by Delaram Kahrobaei and Vladimir Shpilrain, Contemporary Mathematics 633 (2015) 13-40.

Crossrefs

A224074 is the number of root classes.

Sequence in context: A093512 A081160 A051437 * A034774 A342536 A172416

Adjacent sequences: A224070 A224071 A224072 * A224074 A224075 A224076

Keyword

nonn,hard

Author

Eric Rowland, Mar 30 2013

Status

approved