i1 : X = specialCubicFourfold("3-nodal septic scroll",ZZ/65521);
o1 : ProjectiveVariety, cubic fourfold containing a surface of degree 7 and sectional genus 0
i2 : describe X
o2 = Special cubic fourfold of discriminant 26
containing a 3-nodal surface of degree 7 and sectional genus 0
cut out by 13 hypersurfaces of degree 3