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%I M4857 #39 Jul 10 2022 14:58:33
%S 1,1,0,0,1,12,104,956,10037,126578,1971005,38569954,958347642,
%T 30400603560,1234260982770,64187360439352,4275470549123119
%N Number of isomorphism classes of connected irreducible posets with n labeled points.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H S. R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/">Series-parallel networks</a>
%H S. R. Finch, <a href="/A000084/a000084_2.pdf">Series-parallel networks</a>, July 7, 2003. [Cached copy, with permission of the author]
%H R. P. Stanley, <a href="http://dx.doi.org/10.1090/S0002-9939-1974-0351928-7">Enumeration of posets generated by disjoint unions and ordinal sums</a>, Proc. Amer. Math. Soc. 45 (1974), 295-299.
%H R. P. Stanley, <a href="/A003277/a003277.pdf">Letter to N. J. A. Sloane, c. 1991</a>
%H J. A. Wright, <a href="/A000798/a000798_4.pdf">Letter to N. J. A. Sloane, Apr 06 1972, listing 18 sequences</a>
%H <a href="/index/Pos#posets">Index entries for sequences related to posets</a>
%Y Cf. A003430, A046906.
%K nonn,nice,more
%O 0,6
%A _N. J. A. Sloane_ and _Richard Stanley_
%E More terms from _Richard Stanley_, Jun 19 2003
%E 2 more terms from _Vladeta Jovovic_, Feb 17 2008
%E Title clarified by _Geoffrey Critzer_, Jul 08 2022
%E a(0) changed to 1 by _Geoffrey Critzer_, Jul 10 2022