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A009946
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Coordination sequence for NiAs(2), Ni position.
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1
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1, 6, 20, 42, 74, 114, 164, 222, 290, 366, 452, 546, 650, 762, 884, 1014, 1154, 1302, 1460, 1626, 1802, 1986, 2180, 2382, 2594, 2814, 3044, 3282, 3530, 3786, 4052, 4326, 4610, 4902, 5204, 5514, 5834, 6162, 6500, 6846, 7202, 7566, 7940, 8322, 8714
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OFFSET
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0,2
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REFERENCES
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Gmelin Handbook of Inorg. and Organomet. Chem., 8th Ed., 1994, TYPIX search code (194) hP4.
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LINKS
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Reticular Chemistry Structure Resource, acs
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FORMULA
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a(0)=1, a(4n)=2*((6n)^2+1), a(4n+2)=18*(2n+1)^2+2, a(2n+1)=6*(3n^2+3n+1). - Ralf Stephan, Mar 07 2004
a(n) = (7+(-1)^n+18*n^2)/4 for n>0.
a(n) = 2*a(n-1)-2*a(n-3)+a(n-4) for n>4.
G.f.: -(x^4+4*x^3+8*x^2+4*x+1) / ((x-1)^3*(x+1)). (End)
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MATHEMATICA
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CoefficientList[Series[-(x^4 + 4 x^3 + 8 x^2 + 4 x + 1)/((x - 1)^3 (x + 1)), {x, 0, 50}], x] (* Vincenzo Librandi, Oct 15 2013 *)
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PROG
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(PARI) Vec(-(x^4+4*x^3+8*x^2+4*x+1)/((x-1)^3*(x+1)) + O(x^100)) \\ Colin Barker, Aug 31 2013
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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