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, 4690276767463069086098564091958080307200, 78882286441940622154458600457858710575410839552

Offset

0,2

Links

Roland Bacher, Apr 08 2008, Table of n, a(n) for n = 0..14

Roland Bacher, The special subgroup of invertible non-commutative rational power series as a metric group, arXiv:0804.1092 [math.CO], 2008.

Formula

The reference contains a somewhat complicated formula.

Crossrefs

Sequence in context: A239164 A209176 A351630 * A133461 A246981 A174745

Adjacent sequences: A137340 A137341 A137342 * A137344 A137345 A137346

Keyword

nonn

Author

Roland Bacher, Apr 08 2008

Status

approved