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A003426
Number of stable trees with n nodes.
(Formerly M1142)
3
1, 1, 1, 1, 2, 4, 8, 17, 37, 85, 196, 469, 1134, 2799, 6975, 17628, 44903, 115497, 299089, 780036, 2045924, 5396078, 14299878, 38067356, 101748748, 272995157, 735004112, 1985356350, 5378958683, 14614641597, 39813346977, 108730631236, 297641593852
OFFSET
1,5
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000 (first 100 terms from Sean A. Irvine)
D. D. Grant, The stability index of graphs, pp. 29-52 of Combinatorial Mathematics (Proceedings 2nd Australian Conf.), Lect. Notes Math. 403, 1974. Gives first 45 terms.
K. L. McAvaney, Counting stable trees, pp. 79-85 of Combinatorial Mathematics (Proceedings 2nd Australian Conf.), Lect. Notes Math. 403, 1974.
FORMULA
a(n) = A000055(n) - A002988(n) + [n <= 2]. - Sean A. Irvine, Feb 13 2016
G.f.: t(x) - b(x) + x + x^2 where t(x) is the g.f. for A000055 and b(x) is the g.f. for A002988. - Sean A. Irvine, Feb 13 2016
CROSSREFS
Cf. A006544 (forests).
Sequence in context: A324936 A358453 A331783 * A179476 A087803 A212658
KEYWORD
nonn
EXTENSIONS
More terms from Sean A. Irvine, Feb 13 2016
STATUS
approved