https://members.loria.fr/PZimmermann...op10-2018.html
Code:
FindGroupOrder := function (p, sigma)
K := GF(p);
v := K ! (4*sigma);
u := K ! (sigma^2-5);
x := u^3;
b := 4*x*v;
a := (v-u)^3*(3*u+v);
A := a/b-2;
x := x/v^3;
b := x^3 + A*x^2 + x;
E := EllipticCurve([0,b*A,0,b^2,0]);
return FactoredOrder(E);
end function;
p:=444391024295554825813920762553875384889500352609895126972409492191251;
sigma:=2807183577;
FindGroupOrder(p,sigma);
[ <2, 3>, <3, 2>, <5, 1>, <7, 1>, <3347, 1>, <4363, 1>, <295751, 1>, <6746549,
1>, <22098383, 1>, <136265083, 1>, <396868981, 1>, <809136473, 1>,
<6258955966441, 1> ]