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A141463
Conjectured to be the complete list of numbers not of the form 2*x^2 + 5*y^2 + 4*triangular number.
8
1, 3, 10, 15, 16, 21, 33, 39, 43, 66, 108, 109, 111, 126, 153, 195, 339, 1359
OFFSET
1,2
LINKS
Ben Kane and Zhi-Wei Sun, On almost universal mixed sums of squares and triangular numbers, arXiv:0808.2761 [math.NT], 2008-2010.
MATHEMATICA
Reap[For[n=1, n <= 1400, n++, If[FindInstance[n == 2x^2 + 5y^2 + 4z(z+1)/2, {x, y, z}, Integers] == {}, Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 01 2018 *)
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 05 2008
STATUS
approved