A120331 Number of polynomials in two noncommuting variables over the field F_2 having complexity or rank n.

1, 1, 6, 72, 1776, 89280, 9065472, 1850148864, 757046525952, 620298979246080, 1017126921430892544, 3336658943759213395968, 21894988380633154342354944, 287369531352172835754234347520, 7543680108676972971562235527692288

Offset

0,3

Links

R. Bacher, Table of n, a(n) for n = 0..24

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.

Example

The six polynomials corresponding to a(2) are: X, Y, X+Y, 1+X, 1+Y, 1+X+Y.

Crossrefs

Cf. A137342.

Sequence in context: A012242 A138446 A099029 * A009523 A009793 A259212

Adjacent sequences: A120328 A120329 A120330 * A120332 A120333 A120334

Keyword

nonn

Author

Roland Bacher, Apr 29 2008

Status

approved