A141463 Conjectured to be the complete list of numbers not of the form 2*x^2 + 5*y^2 + 4*triangular number.

1, 3, 10, 15, 16, 21, 33, 39, 43, 66, 108, 109, 111, 126, 153, 195, 339, 1359

Offset

1,2

Links

Table of n, a(n) for n=1..18.

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 *)

Crossrefs

Cf. A141273, A141386, A141423, A141428, A141443.

Cf. A141464, A141491, A141497.

Sequence in context: A328091 A048852 A226101 * A134102 A173600 A328987

Adjacent sequences: A141460 A141461 A141462 * A141464 A141465 A141466

Keyword

nonn

Author

N. J. A. Sloane, Sep 05 2008

Status

approved