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%I #10 Sep 13 2021 16:03:40
%S 0,-1,0,-1,1,2,2,2,3,4,6,6,8,8,11,13,15,17,19,22,27,29,33,36,42,47,52,
%T 57,63,70,78,84,93,100,110,120,130,140,151,163,177,189,203,216,233,
%U 249,265,282,300,319,340,359,381,402,426,450,475,500,526,554,584
%N Dimension arising in an indefinite quaternion algebra over Q.
%C See reference for precise definition. The definition makes sense only for n > 4. All terms are generated using the formula given by Kitayama (and here in the Python code), but for n <= 4 they don't have meaningful interpretation.
%H Hidetaka Kitayama, <a href="https://arxiv.org/abs/1004.5164">On the graded ring of Siegel modular forms of degree two with respect to a non-split symplectic group</a>, arXiv:1004.5164 [math.NT], 2010. See table at p. 4.
%H Hidetaka Kitayama, <a href="https://doi.org/10.1142/S0129167X12500322">On the graded ring of Siegel modular forms of degree two with respect to a non-split symplectic group</a>, International Journal of Mathematics 23 (2012), 1250032. See Sec. 2.3.
%o (Python)
%o [(4*k**3-18*k**2+696*k-1737+(-1)**k*225 + [0,-1,1][k%3]*160 + [1,0,0,-1][k%4]*360 + [1,0,0,-1,0][k%5]*1152) // 1440 for k in range(100)] # _Andrey Zabolotskiy_, Sep 13 2021
%K sign
%O 0,6
%A _Jonathan Vos Post_, Apr 29 2010
%E Terms a(11) and beyond from _Andrey Zabolotskiy_, Sep 13 2021