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A058349
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Number of connected labeled series-parallel posets on n nodes.
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3
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1, 2, 12, 122, 1740, 31922, 715932, 18978122, 580513260, 20125554242, 779832497532, 33398722757402, 1566656717322060, 79879485803841362, 4398701789915269212, 260166428897541369962, 16449181879032096013740
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| R. P. Stanley, Enumeration of posets generated by disjoint unions and ordinal sums. Proc. Amer. Math. Soc. 45 (1974), 295-299
R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.39, page 133, g(n).
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LINKS
| Index entries for sequences related to posets
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MAPLE
| (continue from A053554) t1 := log(1+EGF053554): t2 := series(t1, x, 30); SERIESTOLISTMULT(t2);
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CROSSREFS
| A053554(n) = A058349(n) + A058350(n) (n>=2).
Sequence in context: A028359 A034524 A051782 * A048173 A013469 A039933
Adjacent sequences: A058346 A058347 A058348 * A058350 A058351 A058352
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KEYWORD
| nonn,easy,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 16 2000
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