OFFSET
0,4
REFERENCES
J. A. Wright, There are 718 6-point topologies, quasi-orderings and transgraphs, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.
LINKS
G. Brinkmann, B. D. McKay, Posets on up to 16 Points, Order 19 (2) (2002) 147-179 (Table III, up to 18 points)
FORMULA
E.g.f.: A(x) = 2-1/B(x), where B(x) is e.g.f. of A001035. - Vladeta Jovovic, Jan 10 2006
MATHEMATICA
A001035 = Cases[Import["https://oeis.org/A001035/b001035.txt", "Table"], {_, _}][[All, 2]]; lg = Length[A001035];
B[x_] = Sum[A001035[[n + 1]] x^n/n!, {n, 0, lg - 1}];
A[x_] = 2 - 1/B[x];
CoefficientList[A[x] + O[x]^lg, x]*Range[0, lg - 1]! (* Jean-François Alcover, Jan 01 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
John A. Wright.
EXTENSIONS
More terms from Vladeta Jovovic, Jan 10 2006
a(16)-a(18) from A001035 by Jean-François Alcover, Jan 01 2020
STATUS
approved