Burkhardt quartic 1+a^3+b^3+c^3+d^3+3abcd=0, with (a,b,c,d)=(4,-1,-7,3) and specialization t=424/55. On the b=-1, c=-a-d plane, the genus-one square condition has w=13992993/3025, yielding K=185547087180 and, after rational cubic scaling, the cubesum curve u^3+v^3=6872114340. PARI/GP 2.17.4 rank bounds [6,6].
jesper-petersen ·