A020678 Numbers of form 3 x^2 + 5 y^2.

0, 3, 5, 8, 12, 17, 20, 23, 27, 32, 45, 47, 48, 53, 57, 68, 72, 75, 80, 83, 92, 93, 95, 107, 108, 113, 120, 125, 128, 137, 147, 152, 153, 155, 167, 173, 180, 183, 188, 192, 197, 200, 207, 212, 227, 228, 233, 237, 243, 245, 248, 255, 257, 263, 272, 288, 293, 300, 305, 317

Offset

1,2

Comments

Discriminant -60.

Links

Table of n, a(n) for n=1..60.

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

Mathematica

With[{upto=320}, Select[Union[3#[[1]]^2+5#[[2]]^2&/@ Tuples[ Range[ 0, Ceiling[ Sqrt[upto]]], 2]], #<+upto&]] (* Harvey P. Dale, May 22 2015 *)

Crossrefs

The primes in this sequence are given by A106859 (excluding 2). - N. J. A. Sloane, Jun 01 2014

Sequence in context: A265060 A320849 A255981 * A310034 A014811 A282513

Adjacent sequences: A020675 A020676 A020677 * A020679 A020680 A020681

Keyword

easy,nonn

Author

David W. Wilson

Status

approved