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A141273 Conjectured to be complete list of numbers not of the form 4*x^2 + 4*y^2 + triangular number. 9
2, 12, 13, 24, 27, 34, 54, 84, 112, 133, 162, 234, 237, 279, 342, 399, 652, 834, 864 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

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-Fran├žois Alcover, Aug 31 2018 *)

CROSSREFS

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

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Sep 05 2008

STATUS

approved

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Last modified August 17 11:14 EDT 2019. Contains 326057 sequences. (Running on oeis4.)