A193297 Triangle read by rows: T(n,k) = number of pairs of partitions of n that have block distance k (n >= 2, 2 <= k <= n).
1, 3, 7, 12, 28, 65, 50, 140, 325, 811, 225, 700, 1950, 4866, 12762, 1092, 3675, 11375, 34062, 89334, 244588, 5684, 20384, 68250, 227080, 714672, 1956704, 5574956, 31572, 119364, 425880, 1532790, 5360040, 17610336, 50174604, 148332645
Offset: 2
Examples
Triangle begins 1 3 7 12 28 65 50 140 325 811 225 700 1950 4866 12762 1092 3675 11375 34062 89334 244588 5684 20384 68250 227080 714672 1956704 5574956 31572 119364 425880 1532790 5360040 17610336 50174604 148332645 ...
Links
- 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.
- Frank Ruskey, Jennifer Woodcock and Yuji Yamauchi, Counting and computing the Rand and block distances of pairs of set partitions, Journal of Discrete Algorithms, Volume 16, October 2012, Pages 236-248. - From _N. J. A. Sloane_, Oct 03 2012