A192105 Number of distinct (unordered) pairs of partitions of a 12-element set that have Rand distance n.

7654350, 40209840, 156637140, 576841320, 1851589872, 5544758076, 14686598520, 35723706480, 75818872580, 144536922420, 242305860072, 370664737190, 506699655660, 643405035240, 746030515164, 812426918688, 833352979140, 795923308950, 741556189440, 644098507272, 547387431756, 444670121610, 349922192400, 268690544925, 197063378424, 147497181678, 99290917440, 73672276095, 45746253960, 32550841950, 19313040780

Offset

1,1

Comments

The Rand distance of a pair of set partitions is the number of unordered pairs {x; y} such that there is a block in one partition containing both x and y, but x and y are in different blocks in the other partition.

Links

Table of n, a(n) for n=1..31.

F. Ruskey and J. 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. A192100 for set sizes 2..7. A192098 and A192102-A192104 for set sizes 8..11.

Sequence in context: A204803 A187962 A080340 * A233597 A258954 A273101

Adjacent sequences: A192102 A192103 A192104 * A192106 A192107 A192108

Keyword

nonn,fini

Author

Frank Ruskey and Yuji Yamauchi (eugene.uti(AT)gmail.com), Aug 08 2011

Status

approved