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 A217298 Triangle read by columns: T(n,k) = number of AVL trees of height n with k (leaf-) nodes, k>=1, A029837(k)<=n
 1, 1, 2, 1, 4, 6, 4, 1, 16, 32, 44, 60, 70, 56, 128, 28, 448, 8, 864, 1, 1552, 2720, 4288, 6312, 9004, 11992, 4096, 14372, 22528, 15400, 67584, 14630, 159744, 11968, 334080, 8104, 644992, 4376, 1195008, 1820, 2158912, 560, 3811904, 120, 6617184, 16, 11307904 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Camb. 1998, p. 239, Eq 79, A_5. D. E. Knuth, Art of Computer Programming, Vol. 3, Sect. 6.2.3 (7) and (8). LINKS Alois P. Heinz, Columns k = 1..1500, flattened Ralf Hinze, Functional Pearls: Purely functional 1-2 brother trees, Journal of Functional Programming, 19(6):633-644, 2009, DOI: 10.1017/S0956796809007333. R. C. Richards, Shape distribution of height-balanced trees, Info. Proc. Lett., 17 (1983), 17-20. Wikipedia, AVL tree Index entries for sequences related to rooted trees EXAMPLE There are 2 AVL trees of height 2 with 3 (leaf-) nodes: o o / \ / \ o N N o / \ / \ N N N N Triangle begins: 1 . 1 . . 2 1 . . . . 4 6 4 1 . . . . . . . 16 32 44 60 70 56 28 8 1 . . . . . . . . . . . . 128 448 864 1552 2720 ... CROSSREFS Triangle read by rows gives: A143897. Row sums give: A029758. Column sums give: A006265. First elements of rows give: A174677. First, last elements of columns give: A217299, A217300. Row lengths give: 1+A008466(n). Column heights give: A217710(k). Cf. A029837, A072649. Sequence in context: A345135 A291057 A143897 * A217299 A333340 A217300 Adjacent sequences: A217295 A217296 A217297 * A217299 A217300 A217301 KEYWORD nonn,look,tabf AUTHOR Alois P. Heinz, Mar 17 2013 STATUS approved

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Last modified February 26 02:39 EST 2024. Contains 370335 sequences. (Running on oeis4.)