A003426 Number of stable trees with n nodes.

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

Author

N. J. A. Sloane

Keywords

• nonn

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.
• Index entries for sequences related to trees

Crossrefs

Cf. A006544 (forests).

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

Extensions

More terms from Sean A. Irvine, Feb 13 2016