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A068244
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1/6 the number of colorings of a 3 X 3 rhombic- or staggered- hexagonal array with n colors.
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3
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1, 176, 5490, 65600, 455875, 2239776, 8647716, 27962880, 78920325, 200002000, 464447126, 1003294656, 2039332295, 3935444800, 7261533000, 12884914176, 22089914121, 36733221360, 59442494650, 93866696000, 144987663051, 219503536736, 326295822700, 476993088000
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OFFSET
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3,2
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COMMENTS
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Numbers for rhombic- and staggered- hexagonal arrays differ above 4 X 4.
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 3..1000
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FORMULA
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From Alois P. Heinz, May 02 2012: (Start)
G.f.: (1089*x^6+10934*x^5+26015*x^4+18500*x^3+3775*x^2+166*x+1) / (x-1)^10*x^3.
a(n) = (n^9 -16*n^8 +112*n^7 -448*n^6 +1120*n^5 -1791*n^4 +1786*n^3 -1012*n^2 +248*n)/6. (End)
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MAPLE
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a:= n-> (248 +(-1012 +(1786 +(-1791 +(1120 +(-448 +(112 +(-16+n)*n) *n) *n) *n) *n) *n) *n) *n/6:
seq(a(n), n=3..40); # Alois P. Heinz, May 02 2012
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CROSSREFS
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Cf. A068239-A068305, A000332, A002417, A027441, A212162, A212163.
Sequence in context: A220919 A221635 A223411 * A283200 A283730 A083961
Adjacent sequences: A068241 A068242 A068243 * A068245 A068246 A068247
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Feb 24 2002
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STATUS
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approved
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