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%I #14 Mar 07 2021 17:35:44
%S 4,7,12,13,19,21,28,31,37,39,43,49,52,57,61,67,73,76,79,84,91,93,97,
%T 103,109,111,124,127,129,133,139,147,148,151,156,157,163,169,172,181,
%U 183,193,196,199,201,211,217,219,223,228,229,237,241,244,247,259,268
%N Positive integers that can be represented in the form x^2 + 3y^2 with (x,y) = 1 and x and y positive.
%C Superset of primes of the form 6n+1 (A002476).
%C For all proper solutions with nonnegative x and y see A244819. - _Wolfdieter Lang_, Mar 02 2021
%H E. Akhtarkavan, M. F. M. Salleh and O. Sidek, <a href="https://www.idosi.org/wasj/wasj21(2)13/2.pdf">Multiple Descriptions Video Coding Using Coinciding Lattice Vector Quantizer for H.264/AVC and Motion JPEG2000</a>, World Applied Sciences Journal 21 (2): 157-169, 2013. - From _N. J. A. Sloane_, Feb 11 2013
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Eulers6nPlus1Theorem.html">Eulers 6n Plus 1 Theorem</a>
%Y Cf. A002476, A092572, A092573, A092575, A244819.
%K nonn
%O 1,1
%A _Eric W. Weisstein_, Feb 28 2004