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A229646
Cogrowth function of the group Baumslag-Solitar(4,4).
10
1, 4, 28, 232, 2092, 19884, 196096, 1988424, 20611116, 217526524, 2330681348, 25296553088, 277653104800, 3077568629256, 34410056828392, 387725845018512, 4399241841920428, 50228061806093020, 576729989899675348
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(4,4)=<a,t | ta^4=a^4t>.
LINKS
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: A359705 A229648 A229647 * A229645 A359798 A307468
KEYWORD
nonn,walk
AUTHOR
Murray Elder, Sep 27 2013
STATUS
approved