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URL: https://oeis.org/A317487

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A317487
Number of 4-cycles in the n-Bruhat graph.
2
0, 0, 0, 6, 90, 1080, 12600, 151200, 1905120, 25401600, 359251200, 5388768000, 85621536000, 1438441804800, 25499650176000, 475993469952000, 9336794987520000, 192071211171840000, 4135933413900288000, 93058501812756480000, 2184137777840578560000, 53390034569436364800000
OFFSET
1,4
LINKS
Jennifer Elder, Pamela E. Harris, Jan Kretschmann, and J. Carlos Martínez Mori, Boolean intervals in the weak order of S_n, arXiv:2306.14734 [math.CO], 2023.
Eric Weisstein's World of Mathematics, Bruhat Graph
Eric Weisstein's World of Mathematics, Graph Cycle
FORMULA
a(n) = n!*(n-2)*(n-3)/8 for n > 1. - Andrew Howroyd, Jul 30 2018
PROG
(PARI) a(n) = if(n > 1, n!*(n-2)*(n-3)/8, 0); \\ Andrew Howroyd, Jul 30 2018
CROSSREFS
Cf. A317486.
Sequence in context: A091800 A336042 A353230 * A037959 A247150 A201073
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Jul 29 2018
EXTENSIONS
Terms a(10) and beyond from Andrew Howroyd, Jul 30 2018
STATUS
approved