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A056642
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Number of linear spaces on n (labeled) points.
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9
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OFFSET
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1,3
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COMMENTS
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Alternatively, number of linear geometries on n (labeled) points. For the unlabeled case see A001200.
Also a(n) = 1 + number of simple rank-3 matroids on n (labeled) elements; a(n) = number of 2-partitions of a set of size n.
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REFERENCES
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L. M. Batten and A. Beutelspacher: The theory of finite linear spaces, Cambridge Univ. Press, 1993 (see the Appendix).
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 303, #42.
J. Doyen, Sur le nombre d'espaces linéaires non isomorphes de n points, Bull. Soc. Math. Belg. 19 (1967), 421-437.
J. A. Thas, Sur le nombre d'espaces linéaires non isomorphes de n points, Bull. Soc. Math. Belg. 21 (1969), 57-66.
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LINKS
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CROSSREFS
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KEYWORD
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nice,more,nonn
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AUTHOR
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W. M. B. Dukes (dukes(AT)stp.dias.ie), Aug 28 2000
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EXTENSIONS
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STATUS
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approved
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