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Search: id:A098928
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| A098928 |
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Number of cubes that can be placed with their vertices in a cubical grid of n X n X n points. |
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+0
1
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| 0, 1, 9, 36, 100, 229, 473, 910, 1648, 2795, 4469
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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I. Larrosa, SMSU Problem Corner.
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FORMULA
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a(n) = (n(n - 1))^2/4 + 4*(n - 5)^3(n>5) + 6(n - 7)^2(n - 5)(n>7) + 4(n - 10)^3(n>10). This is valid only for 0 <= n <= 11. For n > 11 further terms must be added.
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EXAMPLE
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a(6)=229 because we can place 15^2 cubes in a 6 X 6 X 6 cubical grid, with its edges parallel to the lattice, plus 4 cubes of edge 3, with a vertex in each face of the lattice and the other two in a diagonal.
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CROSSREFS
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Sequence in context: A085037 A000537 A114286 this_sequence A139469 A103158 A023872
Adjacent sequences: A098925 A098926 A098927 this_sequence A098929 A098930 A098931
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KEYWORD
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more,nonn
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AUTHOR
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Ignacio Larrosa Canestro (ilarrosa(AT)mundo-r.com), Oct 19 2004, Sep 29 2009
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