A229645 Cogrowth function of the group Baumslag-Solitar(3,3).

1, 4, 28, 232, 2108, 20364, 205696, 2149956, 23087260, 253400200, 2831688428, 32121034928, 368996930720, 4284878088040, 50221403053556, 593400572917032, 7061298334083484, 84555438345880932, 1018170456984477856, 12321676227943830972

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(3,3)=<a,t | ta^3=a^3t>.

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: A229648 A229647 A229646 * A359798 A307468 A202824

Adjacent sequences: A229642 A229643 A229644 * A229646 A229647 A229648

Keyword

nonn,walk

Author

Murray Elder, Sep 27 2013

Status

approved