0,3

a(17)-a(18) are from Brinkmann's and McKay's paper. - Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 10 2007

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Moussa Benoumhani, The Number of Topologies on a Finite Set, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.6.

J. I. Brown and S. Watson, The number of complements of a topology on n points is at least 2^n (except for some special cases), Discr. Math., 154 (1996), 27-39.

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 229.

M. Erne' and K. Stege, Counting Finite Posets and Topologies, Order, 8 (1991), 247-265.

J. W. Evans, F. Harary and M. S. Lynn, On the computer enumeration of finite topologies, Commun. ACM, 10 (1967), 295-297, 313.

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 243.

J. Heitzig and J. Reinhold, The number of unlabeled orders on fourteen elements, Order 17 (2000) no. 4, 333-341.

D. J. Kleitman and B. L. Rothschild, The number of finite topologies, Proc. Amer. Math. Soc., 25 (1970), 276-282.

M. Rayburn, On the Borel fields of a finite set, Proc. Amer. Math.. Soc., 19 (1968), 885-889.

A. Shafaat, On the number of topologies definable for a finite set, J. Austral. Math. Soc., 8 (1968), 194-198.

For further references concerning the enumeration of topologies and posets see under A001035.

Gunnar Brinkmann and Brendan D. McKay, Posets on up to 16 points.

S. R. Finch, Transitive relations, topologies and partial orders

Institut f. Mathematik, Univ. Hanover, Erne/Heitzig/Reinhold papers

G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.

D. Rusin, More info and references

N. J. A. Sloane, Classic Sequences

Index entries for "core" sequences

Related to A000798 by A000798(n) = Sum Stirling2(n, k)*A001035(k).

Cf. A000798 (labeled topologies), A001035 (labeled posets), A001930 (unlabeled topologies), A000112 (unlabeled posets), A006057.

Sequence in context: A118795 A099700 A137646 this_sequence A135485 A162287 A166168

Adjacent sequences: A000795 A000796 A000797 this_sequence A000799 A000800 A000801

nonn,nice,core,hard

N. J. A. Sloane (njas(AT)research.att.com).

Two more terms from Jobst Heitzig (heitzig(AT)math.uni-hannover.de), Jul 03 2000