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A055427
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Number of points in Z^n of norm <= 3.
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2
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1, 7, 29, 123, 425, 1343, 4197, 12435, 33809, 84663, 198765, 444907, 959801, 2005615, 4064821, 7988867, 15221537, 28122727, 50423741, 87851099, 148962249, 246243487, 397527813, 627798387, 971451697, 1475103511, 2201030157
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OFFSET
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0,2
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LINKS
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FORMULA
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Appears to satisfy a 9-degree polynomial. - Ralf Stephan, Mar 07 2004
Empirical g.f.: (x+1)*(93*x^8+620*x^7-848*x^6+516*x^5-150*x^4+20*x^3+8*x^2-4*x+1) / (x-1)^10. - Colin Barker, Jul 07 2013
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MATHEMATICA
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a[n_] := SeriesCoefficient[1/(1-x) Sum[x^(i^2), {i, -3, 3}]^n, {x, 0, 9}];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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