This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A240067 #12 Sep 01 2019 08:43:16
%S A240067 2,2,0,0,0,0,0,0,2,1,1,1,1,0,0,0,2,1,1,1,0,1,0,0,2,1,1,1,0,0,1,0,2,1,
%T A240067 1,1,0,0,0,1,2,1,1,1,0,0,0,-1,2,1,1,1,0,0,-1,0,2,1,1,1,0,-1,0,0,2,1,1,
%U A240067 1,-1,0,0,0,2,1,1,0,1,1,0,0,2,1,1,0,1,0,1,0
%N A240067 Twice prime octonion integers shown as 8-vectors sorted by norm and then real and 7 imaginary components.
%C A240067 The norm of an octonion is the sum of the squares of its components. Some authors use the square root of that number. There are 9328 octonions having norm 2. The first 11 are shown above. Counting octonions having just nonnegative entries, there are 309 having norm 2; see A240066.
%D A240067 John H. Conway and Derek A. Smith, On Quaternions and Octonions, CRC, 2003.
%H A240067 John C. Baez, <a href="https://arxiv.org/abs/math/0105155">The Octonions</a>, arXiv:math/0105155 [math.RA], 2001-2002.
%H A240067 Wikipedia, <a href="http://en.wikipedia.org/wiki/Octonion">Octonion</a>
%t A240067 Reverse[Rest[Union[Flatten[Table[If[(a/2)^2 + (b/2)^2 + (c/2)^2 + (d/2)^2 + (e/2)^2 + (f/2)^2 + (g/2)^2 + (h/2)^2 == 2, {a, b, c, d, e, f, g, h}, {0}], {a, -2, 2}, {b, -2, 2}, {c, -2, 2}, {d, -2, 2}, {e, -2, 2}, {f, -2, 2}, {g, -2, 2}, {h, -2, 2}], 7]]]]
%Y A240067 Cf. A239395 (twice prime nonnegative Hurwitz quaternions), A240066.
%K A240067 sign
%O A240067 1,1
%A A240067 _T. D. Noe_, Mar 31 2014