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A020677 Numbers of form 3*x^2 + 4*y^2. 1

%I

%S 0,3,4,7,12,16,19,27,28,31,36,39,43,48,52,63,64,67,75,76,79,84,91,100,

%T 103,108,111,112,124,127,139,144,147,148,151,156,163,171,172,175,183,

%U 192,196,199,208,211,219,223,228,243,244,247,252,256,259,268,271,279,283,291

%N Numbers of form 3*x^2 + 4*y^2.

%C Each of these numbers is congruent to 0, 3, 4 or 7 mod 12. Therefore, except for 3, all the primes in this sequence are of the form 12k + 7. - _Alonso del Arte_, Jan 23 2014

%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 max = 300; Select[Union[Flatten[Table[3x^2 + 4y^2, {x, 0, Ceiling[Sqrt[max/3]]}, {y, 0, Ceiling[Sqrt[max/4]]}]]], # < max &] (* _Alonso del Arte_, Jan 23 2014 *)

%Y Cf. A068229.

%K easy,nonn

%O 1,2

%A _David W. Wilson_

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Last modified September 26 08:03 EDT 2021. Contains 347664 sequences. (Running on oeis4.)