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A147860
Number of consistent sets of 6 irreflexive binary order relationships over n objects.
8
24, 7960, 240480, 2934568, 21663936, 115970400, 495329520, 1787153280, 5652862776, 16082870232, 41929743856, 101579030280, 231145969600, 498267767424, 1024487280288, 2020455667392, 3839788818840, 7059475223640, 12597342069312, 21880343758504, 37081456651008
OFFSET
4,1
LINKS
V. I. Rodionov, On the number of labeled acyclic digraphs, Discr. Math. 105 (1-3) (1992), 319-321.
FORMULA
a(n) = (n-3)*(n-2)*(n-1)*n*(n^8 - 26*n^6 - 60*n^5 + 131*n^4 + 1200*n^3 + 3374*n^2 - 4140*n - 44640)/720. - Vaclav Kotesovec, Apr 11 2020
CROSSREFS
Related sequences for the number of consistent sets of k irreflexive binary order relationships over n objects: A147796 (k = 3), A147817 (k = 4), A147821 (k = 5), A147872 (k = 7), A147881 (k = 8), A147883 (k = 9), A147964 (k = 10).
Column k = 6 of A081064.
Sequence in context: A088616 A158042 A297049 * A159409 A167824 A266658
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 04 2009
EXTENSIONS
More terms from Vaclav Kotesovec, Apr 11 2020
Offset changed to n=4 by Petros Hadjicostas, Apr 11 2020
STATUS
approved