| Curve name |
$X_{2a}$ |
| Index |
$4$ |
| Level |
$4$ |
| Genus |
$0$ |
| Does the subgroup contain $-I$? |
No |
| Generating matrices |
$
\left[ \begin{matrix} 1 & 1 \\ 1 & 2 \end{matrix}\right],
\left[ \begin{matrix} 1 & 0 \\ 2 & 3 \end{matrix}\right]$ |
| Images in lower levels |
| Level | Index of image | Corresponding curve |
| $2$ |
$2$ |
$X_{2}$ |
|
| Meaning/Special name |
|
| Chosen covering |
$X_{2}$ |
| Curves that $X_{2a}$ minimally covers |
|
| Curves that minimally cover $X_{2a}$ |
|
| Curves that minimally cover $X_{2a}$ and have infinitely many rational
points. |
|
| Model |
$\mathbb{P}^{1}$, a universal elliptic curve over an appropriate base is
given by
\[y^2 = x^3 + A(t)x + B(t), \text{ where}\]
\[A(t) = -27t^{6} - 139968t^{4} - 241864704t^{2} - 139314069504\]
\[B(t) = 54t^{9} + 373248t^{7} + 967458816t^{5} + 1114512556032t^{3} +
481469424205824t\]
|
| Info about rational points |
| Comments on finding rational points |
None |
| Elliptic curve whose $2$-adic image is the subgroup |
$y^2 = x^3 + x^2 - 114x - 127$, with conductor $196$ |
| Generic density of odd order reductions |
$121/168$ |