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A113174
Number of fixed 3D piled polyominoes: polycubes with fixed orientation, with no cubes "sitting on air".
0
1, 3, 11, 44, 184, 792, 3484, 15592, 70745, 324561, 1502511, 7007929, 32892778, 155221536, 735915652, 3503270920, 16737092549, 80218277681, 385574074383, 1858059853316, 8974761939239, 43441619693731, 210682920968681
OFFSET
1,2
FORMULA
a(n) = sum_{m=1}^n A001168(m)*C(n-1, m-1). If both sequences are shifted left, binomial transform of A001168.
EXAMPLE
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.
CROSSREFS
Cf. A001168, A001931 (fixed polycubes).
Sequence in context: A059714 A059715 A026748 * A132840 A372535 A091200
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected by Franklin T. Adams-Watters, Oct 25 2006
STATUS
approved