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A133330
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Sums of exactly three positive octahedral numbers A005900.
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1
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3, 8, 13, 18, 21, 26, 31, 39, 44, 46, 51, 56, 57, 64, 69, 82, 87, 89, 92, 94, 97, 105, 107, 110, 123, 130, 132, 135, 148, 153, 158, 166, 171, 173, 176, 184, 189, 191, 196, 209, 214, 232, 233, 234, 237, 238, 243, 250, 251, 255, 256, 269, 275, 276, 281, 293, 294
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OFFSET
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1,1
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REFERENCES
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Dickson, L. E. History of the Theory of Numbers, Vol. 2: Diophantine Analysis. New York: Dover, 2005, cites the Pollock reference.
Pollock, F. "On the Extension of the Principle of Fermat's Theorem of the Polygonal Numbers to the Higher Orders of Series Whose Ultimate Differences Are Constant. With a New Theorem Proposed, Applicable to All the Orders." Abs. Papers Commun. Roy. Soc. London 5, 922-924, 1843-1850.
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LINKS
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Table of n, a(n) for n=1..57.
Agustin Moreno Canadas, On sums of figurate numbers by using techniques of poset representation theory, arXiv:0806.2486 [math.NT], 2008.
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MATHEMATICA
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lim = 300; oc[n_] := (2*n^3 + n)/3; nmax = Floor[Solve[oc[n] + oc[1] + oc[1] == lim, n][[1, 1, 2]]]; t = Table[ oc[n], {n, nmax}]; Select[ Union[ Flatten[ Outer[ Plus, t, t, t]]], # <= lim &] (* Jean-François Alcover, Sep 08 2011 *)
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CROSSREFS
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Cf. A005900, A053676, A053677, A053678.
Sequence in context: A197062 A010064 A310304 * A190505 A310305 A184921
Adjacent sequences: A133327 A133328 A133329 * A133331 A133332 A133333
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post, Oct 18 2007
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STATUS
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approved
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