## The modular curve $X_{84k}$

Curve name $X_{84k}$
Index $48$
Level $8$
Genus $0$
Does the subgroup contain $-I$? No
Generating matrices $\left[ \begin{matrix} 5 & 5 \\ 0 & 5 \end{matrix}\right], \left[ \begin{matrix} 5 & 0 \\ 0 & 1 \end{matrix}\right], \left[ \begin{matrix} 3 & 3 \\ 0 & 1 \end{matrix}\right]$
Images in lower levels
 Level Index of image Corresponding curve $2$ $3$ $X_{6}$ $4$ $12$ $X_{13h}$
Meaning/Special name
Chosen covering $X_{84}$
Curves that $X_{84k}$ minimally covers
Curves that minimally cover $X_{84k}$
Curves that minimally cover $X_{84k}$ and have infinitely many rational points.
Model $\mathbb{P}^{1}$, a universal elliptic curve over an appropriate base is given by $y^2 = x^3 + A(t)x + B(t), \text{ where}$ $A(t) = -27t^{8} - 108t^{6} + 270t^{4} + 756t^{2} - 27$ $B(t) = 54t^{12} + 324t^{10} + 2430t^{8} + 7560t^{6} + 5346t^{4} - 3564t^{2} - 54$
Elliptic curve whose $2$-adic image is the subgroup $y^2 = x^3 - x^2 - 80x + 2400$, with conductor $240$
Generic density of odd order reductions $9/112$