B0 white a0
de Bruijn run over the four backgrounds.
B1 white a1
white to white, so the band is redundant.
B2 grey a2
white to grey.
B3 white a0
grey to white, flat.
B4 bluedark a1
white to bluedark.
B5 white a2
bluedark to white.
B6 green a0
white to green, flat.
B7 grey a1
green to grey.
B8 grey a2
grey to grey, band redundant on a slant.
B9 bluedark a0
grey to bluedark, flat.
B10 grey a1
bluedark to grey.
B11 green a2
grey to green.
B12 bluedark a0
green to bluedark, two darks meeting flat.
B13 bluedark a1
bluedark to bluedark.
B14 green a2
bluedark to green.
B15 green a0
green to green, flat.
B16 white a1
green to white, closing the run.