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Search: id:A046001
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| A046001 |
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Maximal number of ordinary double points on an n-th degree algebraic surface in complex projective 3-space. |
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+0
1
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OFFSET
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1,3
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REFERENCES
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S. Endrass, Flaechen mit vielen Doppelpunkten. DMV-Mitteilungen 4 (April 1995), 17-20.
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LINKS
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S. Endrass, Surfaces with many ordinary nodes
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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For n = 3 there is a unique surface of degree 3 with 4 double points, Cayley's cubic: 4(w^3+x^3+y^3+z^3) = (w+x+y+z)^3.
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CROSSREFS
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Sequence in context: A121054 A031003 A036345 this_sequence A031050 A119677 A126032
Adjacent sequences: A045998 A045999 A046000 this_sequence A046002 A046003 A046004
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KEYWORD
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nonn,nice,hard
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AUTHOR
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Eric Weisstein (eric(AT)weisstein.com)
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EXTENSIONS
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For n >= 7 lower bounds are 93,168,216,345; upper bounds are 104, 174, 246, 360
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