cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A334248 Number of distinct acyclic orientations of the edges of an n-dimensional cube.

Original entry on oeis.org

1, 1, 3, 54, 511863, 12284402192625939
Offset: 0

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Author

Matthew Scroggs, Apr 20 2020

Keywords

Comments

a(n) is the number of acyclic orientations of the edges of an n-dimensional cube, with rotations and reflections of the same orientation not counted.
Except for n=0 and n=2, a(n) can be obtained by substituting -1 for x in the chromatic polynomials given in A334358. This fails for n = 2 because the square when folded diagonally gives a graph with an odd number of vertices. The contribution from this graph needs to be negated when determining the number of acyclic orientations. - Andrew Howroyd, Apr 24 2020

Crossrefs

Cf. A333418. A334247 is the number of acyclic orientations with rotations and reflections of the same orientation included.
Cf. A334358.

Formula

a(n) = Sum_{k=1..2^n} (-1)^k * A334358(n, 2^n-k)/(n!*2^n) for n >= 3. - Andrew Howroyd, Apr 24 2020

Extensions

a(5) from Andrew Howroyd, Apr 24 2020

A333444 Number of 2-colorings of edges of the n-cube up to isometry.

Original entry on oeis.org

2, 6, 144, 11251322, 314824456456819827136, 136221825854745676520058554256163406987047485113810944
Offset: 1

Views

Author

Peter Kagey, Mar 21 2020

Keywords

Comments

Bounded below by ceiling(2^A001787(n)/A000165(n)).

Crossrefs

Row sums of A333418.
Showing 1-2 of 2 results.