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%I #14 Jan 01 2020 10:29:55
%S 1,1,2,11,147,3412,121553,6353629,476850636,50811255045,7636459252135,
%T 1610584897516674,474333338553730879,194055026319667963777,
%U 109692570582311591696890,85221064877720762475072503,90542406571528792666541430863,130936936785995060562730057163556,256634185641525450158992588551158389
%N Number of irreducible quasiorders with n labeled points.
%H J. A. Wright, <a href="https://www.ams.org/journals/notices/197006/197006FullIssue.pdf">There are 718 6-point topologies, quasi-orderings and transgraphs</a>, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.
%H J. A. Wright, <a href="/A000798/a000798_4.pdf">Letter to N. J. A. Sloane, Apr 06 1972, listing 18 sequences</a>
%F E.g.f.: A(x) = 2-1/B(x), where B(x) is e.g.f. of A000798. - _Vladeta Jovovic_, Jan 10 2006
%t A000798 = Cases[Import["https://oeis.org/A000798/b000798.txt", "Table"], {_, _}][[All, 2]]; lg = Length[A000798];
%t B[x_] = Sum[A000798[[n + 1]] x^n/n!, {n, 0, lg - 1}];
%t A[x_] = 2 - 1/B[x];
%t CoefficientList[A[x] + O[x]^lg, x]*Range[0, lg - 1]! (* _Jean-François Alcover_, Jan 01 2020 *)
%Y Cf. A046911.
%K nonn,more
%O 0,3
%A John A. Wright.
%E Corrected and extended by _Vladeta Jovovic_, Jan 10 2006
%E a(16)-a(18) from A000798 by _Jean-François Alcover_, Jan 01 2020
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