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A141273
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Conjectured to be complete list of numbers not of the form 4*x^2 + 4*y^2 + triangular number.
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9
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2, 12, 13, 24, 27, 34, 54, 84, 112, 133, 162, 234, 237, 279, 342, 399, 652, 834, 864
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..19.
Ben Kane and Zhi-Wei Sun, On almost universal mixed sums of squares and triangular numbers, arXiv:0808.2761
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MATHEMATICA
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r[k_] := Reduce[x >= 0 && y >= 0 && z >= 0 && k == 4x^2 + 4y^2 + z(z+1)/2, {x, y, z}, Integers];
Reap[For[k=1, k <= 1000, k++, If[r[k]===False, Print[k]; Sow[k]]]][[2, 1]] (* Jean-François Alcover, Aug 31 2018 *)
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CROSSREFS
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Cf. A001481, A141386, A141423, A141428, A141443, A141463.
Cf. A141464, A141491, A141497.
Sequence in context: A032931 A072483 A081539 * A010097 A103761 A286241
Adjacent sequences: A141270 A141271 A141272 * A141274 A141275 A141276
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Sep 05 2008
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STATUS
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approved
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