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

Author

Andrew Elvey Price, Jan 11 2023

Keywords

• nonn
• walk

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.

Examples

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

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.