A141428 Conjectured to be complete list of numbers not of the form x^2 + 5*y^2 + 3*triangular number.

2, 11, 26, 37, 40, 53, 62, 142, 220, 425, 692

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Ben Kane and Zhi-Wei Sun, On almost universal mixed sums of squares and triangular numbers, arXiv:0808.2761

Mathematica

Reap[For[n = 1, n <= 700, n++, If[FindInstance[n == x^2 + 5y^2 + 3z(z+1)/2, {x, y, z}, Integers] == {}, Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 01 2018 *)

Crossrefs

Cf. A141273, A141386, A141423, A141443, A141463.

Cf. A141464, A141491, A141497.

Sequence in context: A241238 A296285 A077482 * A371344 A104085 A080663

Adjacent sequences: A141425 A141426 A141427 * A141429 A141430 A141431

Keyword

nonn

Author

N. J. A. Sloane, Sep 05 2008

Status

approved