A229649 Cogrowth function of the group Baumslag-Solitar(7,7).

1, 4, 28, 232, 2092, 19864, 195352, 1970896, 20275692, 211825564, 2240852928, 23952708696, 258285519688, 2806105225928, 30685515254240, 337472968923532, 3730218568024236, 41417273400310152, 461722437389957236, 5166105817092273412

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(7,7)=<a,t | ta^7=a^7t>.

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: A229652 A229651 A229650 * A359705 A229648 A229647

Adjacent sequences: A229646 A229647 A229648 * A229650 A229651 A229652

Keyword

nonn,walk

Author

Murray Elder, Sep 27 2013

Status

approved