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A028964 Numbers represented by quadratic form with Gram matrix [ 2, 1, 1; 1, 4, 2; 1, 2, 4 ], divided by 2. 0

%I #8 Mar 31 2012 10:30:16

%S 0,1,2,3,4,5,6,7,8,9,11,12,13,14,16,17,18,19,20,21,22,23,24,25,26,27,

%T 28,29,30,31,32,33,34,36,37,38,39,41,42,43,44,45,46,47,48,49,50,51,52,

%U 53,54,55,56,57,58,59,61,62,63,64,66,67,68,69,70,71,72,73,74,75,76,77

%N Numbers represented by quadratic form with Gram matrix [ 2, 1, 1; 1, 4, 2; 1, 2, 4 ], divided by 2.

%p L := [seq(0,i=1..1)]: for x from -20 to 20 do for y from -20 to 20 do for z from -20 to 20 do if member(2*x^2+2*x*y+2*x*z+4*y^2+4*y*z+4*z^2, L)=false then L := [op(L), 2*x^2 +2*x*y+2*x*z+4*y^2+4*y*z+4*z^2] fi: od: od: od: L2 := sort(L): for i from 1 to 100 do printf(`%d, `,L2[i]/2) od:

%K nonn

%O 1,3

%A _N. J. A. Sloane_.

%E More terms from _James A. Sellers_, May 31 2000

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)