%I M2532 #33 May 03 2019 21:35:27
%S 1,3,6,9,15,20,26,34,41
%N Leech's tree-labeling problem for n nodes.
%C a(11) >= 48, a(12) >= 55.
%C a(n) is the greatest number k such that there exists a tree with n nodes and integral edge labels such that for each integer 1 <= m <= k, there exists a pair of nodes such that the sum of the edge labels on the path connecting the two nodes equals m. - _Charlie Neder_, Apr 26 2019
%D R. K. Guy, Unsolved Problems in Number Theory, Sect. C10.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H R. K. Guy, <a href="https://www.jstor.org/stable/2324219">A quarter century of "Monthly" unsolved problems</a>, 1969-1993, Amer Math. Monthly, 100 (1993), 945-949.
%H J. Leech, <a href="https://doi.org/10.1112/jlms/s1-31.2.160">On the representation of 1, 2, ..., n by differences</a>, J. Lond. Math. Soc. 31 (1956), 160-169.
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%Y Cf. A005488.
%K nonn,hard,nice,more
%O 2,2
%A _N. J. A. Sloane_