A029718 Numbers of form 2x^2 + 2xy + 3y^2.

0, 2, 3, 7, 8, 10, 12, 15, 18, 23, 27, 28, 32, 35, 40, 42, 43, 47, 48, 50, 58, 60, 63, 67, 72, 75, 82, 83, 87, 90, 92, 98, 103, 107, 108, 112, 115, 122, 123, 127, 128, 135, 138, 140, 147, 160, 162, 163, 167, 168, 172, 175, 178, 183, 188, 192, 200, 202, 203, 207, 210

Offset

1,2

Comments

Numbers represented by quadratic form with Gram matrix [ 2, 1; 1, 3 ].

References

H. Cohn, A second course in number theory, John Wiley & Sons, Inc., New York-London, 1962. see page 3.

Links

Table of n, a(n) for n=1..61.

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

Formula

List contains 0 and all positive n such that 2*A035170(n) = A028586(n) is nonzero. - Michael Somos, Oct 21 2006

Crossrefs

Cf. A028927.

For primes see A106865.

For the properly represented numbers see A344232.

Sequence in context: A047532 A225378 A028808 * A206821 A323003 A051468

Adjacent sequences: A029715 A029716 A029717 * A029719 A029720 A029721

Keyword

nonn

Author

N. J. A. Sloane

Extensions

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

Status

approved