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%I #11 Jan 20 2016 17:57:31
%S 0,5,7,12,20,27,28,33,45,48,52,63,68,73,80,83,87,108,112,117,125,132,
%T 143,153,157,175,180,187,188,192,195,208,220,237,243,245,252,255,257,
%U 272,273,292,297,300,308,320,327,332,343,348,355,357,363,377,383,388,405,412,420
%N Numbers of form 5 x^2 + 7 y^2.
%H Harvey P. Dale, <a href="/A020686/b020686.txt">Table of n, a(n) for n = 1..1000</a>
%H N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)
%t Module[{upto=500,nn},nn=Ceiling[Sqrt[upto/5]];Select[Union[5#[[1]]^2+ 7#[[2]]^2 &/@ Tuples[Range[0,nn],2]],#<=upto&]] (* _Harvey P. Dale_, Jan 20 2016 *)
%K easy,nonn
%O 1,2
%A _David W. Wilson_