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A028954 Numbers represented by quadratic form with Gram matrix [ 2, 1; 1, 6 ]. (divided by 2). 4
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois Alcover, Oct 31 2016 *)

CROSSREFS

Cf. A028927. For primes see A056874.

Sequence in context: A035236 A047600 A010384 * A035247 A039885 A239197

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

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Last modified January 17 10:59 EST 2019. Contains 319218 sequences. (Running on oeis4.)