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A357242 Number of n node tournaments that have exactly two circular triads. 3
24, 240, 2240, 21840, 228480, 2580480, 31449600, 412473600, 5801241600, 87178291200, 1394852659200, 23683435776000, 425430061056000, 8062248370176000, 160770717499392000, 3365514444644352000, 73798027581358080000, 1691677863018823680000, 40464026199993876480000 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Table of n, a(n) for n=4..22.

J. B. Kadane, Some equivalence classes in paired comparisons, The Annals of Mathematical Statistics, 37 (1966), 488-494.

FORMULA

a(n) = n!*(n - 3 + (1/18)*(n - 4)*(n - 5)) (proven by Kadane).

EXAMPLE

For n = 4 the a(4) = 24 solution is 4!*(4 - 3 + (1/18)*(4 - 4)*(4 - 5)) = 24.

PROG

(R) fact(n)*(n-3+(1/18)*(n-4)*(n-5))

CROSSREFS

Sequence in context: A353119 A052520 A052724 * A000536 A151720 A052652

Adjacent sequences: A357239 A357240 A357241 * A357243 A357244 A357245

KEYWORD

nonn,easy

AUTHOR

Ian R Harris, Sep 19 2022

STATUS

approved

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Last modified November 30 19:14 EST 2022. Contains 358453 sequences. (Running on oeis4.)