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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Sean A. Irvine and 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.

Index entries for sequences related to trees

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: A203019 A004148 A085022 * A179476 A087803 A212658

Adjacent sequences:  A003423 A003424 A003425 * A003427 A003428 A003429

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Sean A. Irvine, Feb 13 2016

STATUS

approved

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Last modified June 25 20:26 EDT 2017. Contains 288730 sequences.