construct/nppc clique

The task

Undirected graph with 20 vertices labelled 0..19 and 121 edges: [[0, 2], [0, 3], [0, 4], [0, 6], [0, 7], [0, 8], [0, 9], [0, 11], [0, 16], [0, 17], [0, 18], [0, 19], [1, 2], [1, 7], [1, 9], [1, 12], [1, 13], [1, 14], [1, 18], [1, 19], [2, 3], [2, 4], [2, 5], [2, 7], [2, 8], [2, 9], [2, 11], [2, 12], [2, 15], [2, 16],…