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A004401 Least number of edges in graph containing all trees on n nodes.
(Formerly M0989)
2
0, 1, 2, 4, 6, 8, 11, 13, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

Chung, F. R. K.; Graham, R. L.; Pippenger, N. On graphs which contain all small trees. II. Combinatorics (Proc. Fifth Hungarian Colloq., Keszthely, 1976), Vol. I, pp. 213-223. Colloq. Math. Soc. Janos Bolyai, 18. North-Holland, Amsterdam, 1978.

R. L. Graham, personal communication.

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

LINKS

Table of n, a(n) for n=1..9.

F. R. K. Chung, R. L. Graham, On graphs which contain all small trees, J. Combinatorial Theory Ser. B 24 (1978), no. 1, 14--23. MR0505812 (58 #21808a)

Paul Tabatabai, Exhaustive search proving a(9) = 16. (Sage script)

Paul Tabatabai, Graph on 9 vertices and 16 edges containing all trees.

Index entries for sequences related to trees

CROSSREFS

Cf. A212555.

Sequence in context: A193766 A262773 A186152 * A022819 A081527 A070978

Adjacent sequences:  A004398 A004399 A004400 * A004402 A004403 A004404

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane, R. K. Guy

EXTENSIONS

a(9) by Paul Tabatabai, Jul 17 2016

STATUS

approved

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Last modified April 25 23:17 EDT 2017. Contains 285426 sequences.