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A020676
Numbers of form 2 x^2 + 9 y^2.
2
0, 2, 8, 9, 11, 17, 18, 27, 32, 36, 38, 41, 44, 50, 54, 59, 68, 72, 81, 83, 86, 89, 98, 99, 107, 108, 113, 128, 131, 134, 137, 144, 146, 152, 153, 162, 164, 171, 176, 179, 194, 198, 200, 209, 216, 225, 227, 233, 236, 242, 243, 251, 257, 272, 275, 278, 281, 288, 297, 306, 323
OFFSET
1,2
LINKS
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
With[{upto = 350}, Select[Union[2#[[1]]^2 + 9#[[2]]^2&/@Tuples[Range[0, Ceiling[Sqrt[upto^2/2]]], 2]], # <= upto &]] (* Harvey P. Dale, May 30 2017 *)
CROSSREFS
Subsequences include A001105, A016766.
Cf. A106949 (prime terms).
Sequence in context: A116039 A030334 A338807 * A086678 A359771 A289146
KEYWORD
easy,nonn
STATUS
approved