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A005387
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Number of partitional matroids on n elements.
(Formerly M1493)
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1
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1, 2, 5, 16, 62, 276, 1377, 7596, 45789, 298626, 2090910, 15621640, 123897413, 1038535174, 9165475893, 84886111212, 822648571314, 8321077557124, 87648445601429, 959450073912136, 10894692556576613, 128114221270929646
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| Recski, A.; Enumerating partitional matroids. Stud. Sci. Math. Hungar. 9 (1974), 247-249 (1975).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..100
Index entries for sequences related to matroids
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FORMULA
| E.g.f.: exp ((x-1)*e^x + 2*x + 1 ).
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CROSSREFS
| Sequence in context: A033543 A124531 A129578 * A173469 A138549 A144188
Adjacent sequences: A005384 A005385 A005386 * A005388 A005389 A005390
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KEYWORD
| nonn,easy,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Aug 21 2000
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