A006870 Number of quasi-orders with n elements. (Formerly M2755)

1, 1, 3, 8, 26, 94, 435, 2564, 19983, 205729

Offset

0,3

References

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

Links

Table of n, a(n) for n=0..9.

M. Erné and K. Stege, The number of partially ordered (labeled) sets, Preprint, 1989. (Annotated scanned copy)

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

Crossrefs

Sequence in context: A148822 A124528 A320344 * A348620 A058802 A054097

Adjacent sequences: A006867 A006868 A006869 * A006871 A006872 A006873

Keyword

nonn,nice,more

Author

N. J. A. Sloane

Status

approved