CoCalc -- LowerCentralSeries

GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it

⁵⁶³⁶⁶⁷ views

HAPBARCODE:=[
[
   [ [[-1], [-1, 1]] ]
],

[
   [ [[1], [1, -2, 1]] ]
]
]
;