A193317 Binomial(n,2)*B(n-1)*(B(n)-B(n-1)), where B() = A000110() are the Bell numbers.

0, 0, 1, 18, 300, 5550, 117780, 2873262, 80126228, 2534723280, 90239747220, 3588582531875, 158318375911740, 7700793136255440, 410691133882551795, 23894146232727414630, 1509723335738373490800, 103169903975944947302744, 7597003720932150826636260, 600748548233457344454385722

Offset: 0

Author

N. J. A. Sloane, Aug 26 2011

Keywords

• nonn

Comments

Sum of the Rand distance over all unordered pairs of partitions.

Links

• Frank Ruskey and Jennifer Woodcock, The Rand and block distances of pairs of set partitions, Combinatorial algorithms, 287-299, Lecture Notes in Comput. Sci., 7056, Springer, Heidelberg, 2011.

Crossrefs

Cf. A000110, A191200.

Equals half A124104.

Programs

Mathematica

Table[Binomial[n, 2]*BellB[n - 1] (BellB[n] - BellB[n - 1]), {n, 19}] (* Michael De Vlieger, Apr 16 2015 *)