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A000398 Numbers of form x^2 + 2y^2 + 2yz + 4z^2. 2

%I #21 Jul 08 2017 01:23:21

%S 0,1,2,3,4,5,6,8,9,11,12,13,14,15,16,17,18,19,20,22,23,24,25,26,27,28,

%T 29,30,31,32,33,34,36,37,38,39,40,41,43,44,45,46,47,48,49,50,51,52,53,

%U 54,55,56,57,58,59,60,61,62,63,64

%N Numbers of form x^2 + 2y^2 + 2yz + 4z^2.

%H Vincenzo Librandi, <a href="/A000398/b000398.txt">Table of n, a(n) for n = 1..1000</a>

%t q=16;imax=q^2;Select[Union[Flatten[Table[x^2+2*y^2+2*y*z+4*z^2,{z,-q,q},{y,0,q},{x,0,q}]]],#<=imax&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 19 2011 *)

%Y Complement of A097634.

%K nonn,easy

%O 1,3

%A _N. J. A. Sloane_

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)