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 A001851 Total diameter of unlabeled trees with n nodes. (Formerly M1363 N0527) 0
 0, 1, 2, 5, 9, 21, 44, 103, 232, 571, 1368, 3441, 8653, 22263, 57518, 150733, 396937, 1054540, 2815453, 7562159, 20399714, 55280532, 150356806, 410432671, 1123902587, 3086827578, 8500975970, 23470712241, 64952794778, 180144093389 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS C program around function Gen() by Gang Li & Frank Ruskey. See C program link. REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS W. Bomfim, Diameters of the trees of order 6 W. Bomfim, C program J. Riordan, Enumeration of trees by height and diameter, IBM J. Res. Dev. 4 (1960), 473-478. J. Riordan, The enumeration of trees by height and diameter, IBM Journal 4 (1960), 473-478. (Annotated scanned copy) EXAMPLE See the trees in first Bomfim link. So a(6) = 21. CROSSREFS Sequence in context: A097163 A117186 A155042 * A356375 A303963 A304349 Adjacent sequences: A001848 A001849 A001850 * A001852 A001853 A001854 KEYWORD nonn AUTHOR EXTENSIONS More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jul 26 2010 a(21)-a(30) from Washington Bomfim, Jan 31 2011 STATUS approved

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Last modified December 7 19:19 EST 2022. Contains 358669 sequences. (Running on oeis4.)