1,3

G. Brinkmann and B. D. McKay, Counting unlabeled topologies and transitive relations, J. Integer Sequences, Volume 8, 2005.

F. Kammuller, Counting idempotent relations, submitted to J. Integer Sequences (2006).

F. Kammuller, Interactive Theorem Proving in Software Engineering, Habilitationsschrift, Technische Universitaet Berlin (2006).

F. Kammuller and J. W. Sanders, Idempotent relations in Isabelle/HOL, International Colloquium on Theoretical Aspects of Computing, ICTAC'04. Volume 3407 of Lecture Motes in Computer Science, Springer-Verlag (2005).

G. Pfeiffer, Counting transitive relations, J. Integer Sequences, Volume 7, 2004, #3.

A relation r is idempotent if r ; r = r, where ; denotes sequential composition

Cf. A000798 (labeled quasi-orders (or topologies)), A001930 (unlabeled quasi-orders), A001035 (labeled partial orders), A000112 (unlabeled partial orders).

Sequence in context: A015499 A039438 A015593 this_sequence A015594 A015596 A163310

Adjacent sequences: A121334 A121335 A121336 this_sequence A121338 A121339 A121340

nonn

Florian Kammuller (flokam(AT)cs.tu-berlin.de), Aug 28 2006