A229651 Cogrowth function of the group Baumslag-Solitar(9,9).

1, 4, 28, 232, 2092, 19864, 195352, 1970896, 20275660, 211823800, 2240795888, 23951292204, 258255572584, 2805537209648, 30675548482880, 337307986673572, 3727607821613388, 41377406950962504, 461130952671387592, 5157535231753964268

Offset

0,2

Comments

a(n) is the number of words of length 2n in the letters a,a^{-1},t,t^{-1} that equal the identity of the group BS(9,9)=<a,t | ta^9=a^9t>.

Links

Murray Elder, Table of n, a(n) for n = 0..49

M. Elder, A. Rechnitzer, E. J. Janse van Rensburg, T. Wong, The cogrowth series for BS(N,N) is D-finite

Index entries for sequences related to groups

Example

For n=1 there are 4 words of length 2 equal to the identity: aa^{-1}, a^{-1}a, tt^{-1}, t^{-1}t.

Crossrefs

The cogrowth sequences for BS(N,N) for N = 1..10 are A002894, A229644, A229645, A229646, A229647, A229648, A229649, A229650, A229651, A229652.

Sequence in context: A089023 A035610 A229652 * A229650 A229649 A359705

Adjacent sequences: A229648 A229649 A229650 * A229652 A229653 A229654

Keyword

nonn,walk

Author

Murray Elder, Sep 28 2013

Status

approved