A028954 Numbers represented by quadratic form with Gram matrix [ 2, 1; 1, 6 ]. (divided by 2).

0, 1, 3, 4, 5, 9, 11, 12, 15, 16, 20, 23, 25, 27, 31, 33, 36, 37, 44, 45, 47, 48, 49, 53, 55, 59, 60, 64, 67, 69, 71, 75, 80, 81, 89, 92, 93, 97, 99, 100, 103, 108, 111, 113, 115, 121, 124, 125, 132, 135, 137, 141, 144, 147, 148, 155, 157, 159, 163, 165, 169, 176, 177

Offset

1,3

Comments

Numbers represented by the form x^2+xy+3y^2 of discriminant -11.

Links

Table of n, a(n) for n=1..63.

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

Mathematica

Reap[For[n = 0, n < 200, n++, r = Reduce[x^2 + x y + 3 y^2 == n, {x, y}, Integers]; If[r =!= False, Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 31 2016 *)

Crossrefs

Cf. A028927. For primes see A056874.

Sequence in context: A047600 A325464 A010384 * A035247 A321995 A353302

Adjacent sequences: A028951 A028952 A028953 * A028955 A028956 A028957

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Mar 29 2000

Status

approved