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Search: id:A113174
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| A113174 |
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Number of fixed 3D piled polyominoes: polycubes with fixed orientation, with no cubes "sitting on air". |
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+0
1
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| 1, 3, 11, 44, 184, 792, 3484, 15592, 70745, 324561, 1502511, 7007929, 32892778, 155221536, 735915652, 3503270920, 16737092549, 80218277681, 385574074383, 1858059853316, 8974761939239, 43441619693731, 210682920968681
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n) = sum_{m=1}^n A001168(m)*C(n-1, m-1). If both sequences are shifted left, binomial transform of A001168.
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EXAMPLE
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For n = 4, there are 4 orientations of the angled tricube excluded: those which set it on a point; this leaves 8 orientations of the angled tricube and 3 of the straight tricube.
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CROSSREFS
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Cf. A001168, A001931 (fixed polycubes).
Sequence in context: A059714 A059715 A026748 this_sequence A132840 A091200 A151105
Adjacent sequences: A113171 A113172 A113173 this_sequence A113175 A113176 A113177
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KEYWORD
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nonn
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AUTHOR
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Frank Adams-Watters (FrankTAW(AT)Netscape.net), Oct 15 2005
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EXTENSIONS
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Corrected by Franklin T. Adams-Watters, Oct 25 2006
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