A224074 Number of root classes of words in F_2 whose minimal words have length n.

1, 0, 0, 0, 2, 0, 0, 0, 13, 0, 0, 0, 304, 0, 0, 0, 11395, 0, 0, 0, 478444, 0, 0, 0

Offset

0,5

Comments

F_2 is the free group on two generators.

a(n) = 0 if n is not divisible by 4.

Links

Table of n, a(n) for n=0..23.

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

A224073 is the number of all equivalence classes.

Sequence in context: A179677 A250397 A348029 * A136615 A283950 A342376

Adjacent sequences: A224071 A224072 A224073 * A224075 A224076 A224077

Keyword

nonn,hard,more

Author

Eric Rowland, Mar 30 2013

Status

approved