A137343 Number of elements of length n with respect to the natural metric in the special group of rational series over the finite field F_2 in two non-commuting variables.
1, 12, 1296, 505536, 679848192, 3248147205120, 57637071142391808, 3930578658351563587584, 1050888530707010579202637824, 1112792971262327168651248131637248
Offset: 0
Keywords
Links
- Roland Bacher, Apr 08 2008, Table of n, a(n) for n = 0..14
- R. Bacher, The special subgroup of invertible non-commutative rational power series as a metric group, arXiv:0804.1092
Formula
The reference contains a somewhat complicated formula.