A359705 Cogrowth sequence of the Brin-Navas group B.

1, 4, 28, 232, 2092, 19864, 195352, 1970896, 20275692, 211825600, 2240855128, 23952786400, 258287602744, 2806152315048, 30686462795856, 337490492639512, 3730522624066540, 41422293291178872, 461802091590831904, 5167329622166765872

Offset

0,2

Comments

This is the number of words of length 2n equal to the identity in the letters t, t^{-1}, a, a^{-1} which generate the Brin-Navas group B.

Links

Andrew Elvey Price, Table of n, a(n) for n = 0..126

Andrew Elvey Price and A. J. Guttmann, Numerical studies of Thompson's group F and related groups, arXiv:1706.07571 [math.GR], 2017.

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

Sequence in context: A229651 A229650 A229649 * A229648 A229647 A229646

Adjacent sequences: A359702 A359703 A359704 * A359706 A359707 A359708

Keyword

nonn,walk

Author

Andrew Elvey Price, Jan 11 2023

Status

approved