%I M2064 #20 Jan 31 2022 01:28:11

%S 2,13,123,1546,24283,457699,10064848,252945467,7151532895,

%T 224661610888,7763387794649,292659248485051,11951855446598278,

%U 525645673381008537,24769319755329986599,1244984053628241578058,66487872534167725541751

%N Generalized weak orders on n points.

%D I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley and Sons, N.Y., 1983.

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

%D C. G. Wagner, Enumeration of generalized weak orders. Arch. Math. (Basel) 39 (1982), no. 2, 147-152.

%H T. D. Noe, <a href="/A004122/b004122.txt">Table of n, a(n) for n = 1..100</a>

%H C. G. Wagner, <a href="/A004121/a004121_1.pdf">Enumeration of generalized weak orders</a>, Preprint, 1980. [Annotated scanned copy]

%H C. G. Wagner and N. J. A. Sloane, <a href="/A004121/a004121.pdf">Correspondence, 1980</a>

%F E.g.f. : 1/(2-exp(x)*exp(exp(x)-1)).

%t With[{nn=20},Rest[CoefficientList[Series[1/(2-Exp[x]Exp[Exp[x]-1]),{x,0,nn}], x] Range[0,nn]!]] (* _Harvey P. Dale_, Nov 05 2011 *)

%Y Cf. A004121, A004123, A000670.

%K nonn,nice,easy

%O 1,1

%A _N. J. A. Sloane_

%E Formula and more terms from _Vladeta Jovovic_, Mar 27 2001