A tree (also called a bicentral tree) having two nodes that are graph centers. The numbers of bicentered trees
on 
,
2, ... nodes are 0, 1, 0, 1, 1, 3, 4, 11, 20, 51, 108 ... (OEIS A000677).
Bicentered Tree
See also
Centered Tree, Graph Center, TreeExplore with Wolfram|Alpha
References
Biggs, N. L.; Lloyd, E. K.; and Wilson, R. J. Graph Theory 1736-1936. Oxford, England: Oxford University Press, p. 49, 1976.Cayley, A. "On the Analytical Forms Called Trees, with Application to the Theory of Chemical Combinations." Reports Brit. Assoc. Advance. Sci. 45, 237-305, 1875. Reprinted in The Collected Mathematical Papers of Arthur Cayley, Vol. 9. Cambridge, England: Cambridge University Press, pp. 427-460, 1896.Sloane, N. J. A. Sequence A000677/M2366 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Bicentered TreeCite this as:
Weisstein, Eric W. "Bicentered Tree." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/BicenteredTree.html