15 3 0 1 1 5 6 2 1 6 7 3 3 4 1 4 2 1 13 5 1 2 3 6 4 5 1 7 3 2 15 8 7 8 1 9 9 10 1 10 11 1 10 11 11 12 1 12 2 14 15 13 14 2 13 14 13 1 12 15 8 9 1 # Generated by triangle spiral