B[1, −2]

Y = x/6 – 1/2

3 + 9t

Excluded because x is even when t is odd

3 + 18t

(3(3 + 18t) + 1)/2 = 5 + 27t

Excluded when t is even

21 + 36t

(3(21 + 36t) + 1)/4 = 16 + 27t

Excluded when t is odd

21 + 72t

(21 + 72t)/6 – 1/2 = 3 + 12t

Star conversion