A022016 Number of partially ordered sets with no isolated points and with n "lines": pairs (a,b) where a < b and there is no c with a < c < b. The lines form the minimal basis for the partial ordering.

1, 1, 4, 12, 47, 174, 749, 3291, 15675, 78104, 411042, 2261961, 13009112, 77860234

Offset: 0

Author

Franklin T. Adams-Watters, Mar 30 2002

Keywords

• nonn
• more

Comments

The points are unlabeled.

Examples

			See Sloane's link.
		

References

• See A000112 for references and links about partially ordered sets.

Links

• N. J. A. Sloane, Illustration of initial terms of A022016 and A022017.

Crossrefs

Cf. A000112, A022017, A342447.

Extensions

a(6)-a(13) from Rico Zöllner and Konrad Handrich, Nov 19 2024