

A334247


Number of acyclic orientations of the edges of an ndimensional cube.


3




OFFSET

0,2


COMMENTS

a(n) is the absolute value of the chromatic polynomial of the nhypercube graph evaluated at 1.


LINKS

Table of n, a(n) for n=0..5.
David Eppstein, 14 acyclic orientations of a square
Eric Weisstein's World of Mathematics, Hypercube Graph


FORMULA

a(n) = Sum_{k=1..2^n} (1)^(2^nk) * k! * A334159(n, k).  Andrew Howroyd, Apr 21 2020


EXAMPLE

For n=2, there are 14 ways to orient the edges of a square without cycles (see links).


CROSSREFS

Cf. A334248 is the number of acyclic orientations with rotations and reflections of the same orientation excluded. A033815 is the analogous sequence for the ndimensional crosspolytope (the dual of the ncube).
Cf. A140986, A158348, A296914, A334159.
Sequence in context: A130421 A227403 A156736 * A277288 A296412 A296410
Adjacent sequences: A334244 A334245 A334246 * A334248 A334249 A334250


KEYWORD

nonn,more


AUTHOR

Matthew Scroggs, Apr 20 2020


EXTENSIONS

a(5) from Andrew Howroyd, Apr 23 2020


STATUS

approved



