A147860 Number of consistent sets of 6 irreflexive binary order relationships over n objects.

24, 7960, 240480, 2934568, 21663936, 115970400, 495329520, 1787153280, 5652862776, 16082870232, 41929743856, 101579030280, 231145969600, 498267767424, 1024487280288, 2020455667392, 3839788818840, 7059475223640, 12597342069312, 21880343758504, 37081456651008

Offset: 4

Author

R. H. Hardin, May 04 2009

Keywords

• nonn

Links

• V. I. Rodionov, On the number of labeled acyclic digraphs, Discr. Math. 105 (1-3) (1992), 319-321.

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.

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

Extensions

More terms from Vaclav Kotesovec, Apr 11 2020

Offset changed to n=4 by Petros Hadjicostas, Apr 11 2020