A020679 - OEIS

A020679

Numbers of form 3*x^2 + 7*y^2.

0, 3, 7, 10, 12, 19, 27, 28, 31, 34, 40, 48, 55, 63, 66, 75, 76, 82, 90, 103, 108, 111, 112, 115, 124, 136, 138, 139, 147, 154, 160, 171, 175, 178, 187, 192, 199, 202, 210, 220, 223, 243, 250, 252, 255, 259, 264, 271, 279, 283, 300, 304, 306, 307, 322, 327, 328, 343, 346

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..59.

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

MATHEMATICA

With[{upto=350}, Select[Union[3#[[1]]^2+7#[[2]]^2&/@Tuples[Range[ 0, Floor[(Sqrt[upto/3])]], 2]], #<+upto&]] (* Harvey P. Dale, Nov 17 2012 *)

CROSSREFS

Sequence in context: A310180 A310181 A310182 * A103541 A183178 A340604

Adjacent sequences: A020676 A020677 A020678 * A020680 A020681 A020682

KEYWORD

easy,nonn

AUTHOR

David W. Wilson

STATUS

approved