A046904 Number of isomorphism classes of posets with n points with property that there is no nonsingleton proper subset T for which x not in T implies x<T or x>T or x incomparable with every element of T.

1, 1, 0, 0, 1, 4, 28, 234

Offset

0,6

Links

Table of n, a(n) for n=0..7.

John A. Wright, There are 718 6-point topologies, quasi-orderings, and transgraphs, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.

John A. Wright, Letter to N. J. A. Sloane, Apr 06 1972, listing 18 sequences.

Index entries for sequences related to posets.

Crossrefs

A subset of the posets enumerated in A003431.

Cf. A046905.

Sequence in context: A359798 A307468 A202824 * A030444 A093877 A393836

Adjacent sequences: A046901 A046902 A046903 * A046905 A046906 A046907

Keyword

nonn,more

Author

John A. Wright

Status

approved