A229648 Cogrowth function of the group Baumslag-Solitar(6,6).

1, 4, 28, 232, 2092, 19864, 195352, 1970924, 20277036, 211864264, 2241723728, 23969620844, 258583473640, 2811005437348, 30762114003572, 338624821158892, 3747021722921964, 41656518905688504, 465062224305678280, 5211973807553021868

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(6,6)=<a,t | ta^6=a^6t>.

Links

Murray Elder, Table of n, a(n) for n = 0..50

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: A229650 A229649 A359705 * A229647 A229646 A229645

Adjacent sequences: A229645 A229646 A229647 * A229649 A229650 A229651

Keyword

nonn,walk

Author

Murray Elder, Sep 27 2013

Status

approved