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 A334248 Number of distinct acyclic orientations of the edges of an n-dimensional cube. 4
 1, 1, 3, 54, 511863, 12284402192625939 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 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 LINKS Matthew Scroggs, Python code to calculate A334248. Stack Exchange Combinatorial problem: Directed Acyclic Graph Eric Weisstein's World of Mathematics, Hypercube Graph Wikipedia, Acyclic orientation 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 CROSSREFS Cf. A333418. A334247 is the number of acyclic orientations with rotations and reflections of the same orientation included. Cf. A334358. Sequence in context: A214006 A154604 A188798 * A193256 A319038 A227054 Adjacent sequences:  A334245 A334246 A334247 * A334249 A334250 A334251 KEYWORD nonn,more AUTHOR Matthew Scroggs, Apr 20 2020 EXTENSIONS a(5) from Andrew Howroyd, Apr 24 2020 STATUS approved

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Last modified April 11 12:00 EDT 2021. Contains 342886 sequences. (Running on oeis4.)