D= 2 (  5,  7):    27 cells,    0 right stones, bones V/S/F = 3/3/3, check: ok
D= 3 (  9, 12):    93 cells,    1 right stones, bones V/S/F = 10/10/10, check: ok
D= 4 ( 13, 17):   198 cells,    3 right stones, bones V/S/F = 21/21/21, check: ok
D=10 ( 37, 47):  1647 cells,   36 right stones, bones V/S/F = 171/171/171, check: ok
D=20 ( 77, 97):  7182 cells,  171 right stones, bones V/S/F = 741/741/741, check: ok
D=30 (117,147): 16617 cells,  406 right stones, bones V/S/F = 1711/1711/1711, check: ok
negative control (t = D-2 instead of D-1): V fails to split into bones for 9 of 9 values D=3..11
checked 2 <= D <= 30; FAILURES: 0 (0.7s)
