stretch tree of depth 17	 check: -1
131072	 trees of depth 4	 check: -131072
32768	 trees of depth 6	 check: -32768
8192	 trees of depth 8	 check: -8192
2048	 trees of depth 10	 check: -2048
512	 trees of depth 12	 check: -512
128	 trees of depth 14	 check: -128
32	 trees of depth 16	 check: -32
long lived tree of depth 16	 check: -1