login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058866 Number of 2-trees rooted at a edge. 8
1, 2, 6, 21, 83, 356, 1599, 7434, 35381, 171508, 843419, 4197179, 21094355, 106915928, 545859112, 2804656069, 14491370996, 75248398034, 392476363133, 2055245992376, 10801442696736, 56953957110855, 301207378815752 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 75, Eq. (3.5.11).

LINKS

Table of n, a(n) for n=1..23.

FORMULA

H. and P. give g.f.

CROSSREFS

Let A063687(n) be the number of 2-trees rooted at a symmetric edge (see H. and P. Eq. (3.5.9)). Then A058866(n) = A058870(n) + A063687(n).

Cf. A058870, A058870, A054581.

Sequence in context: A148495 A150221 A063689 * A178325 A087649 A328435

Adjacent sequences:  A058863 A058864 A058865 * A058867 A058868 A058869

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jan 06 2001

EXTENSIONS

More terms from Vladeta Jovovic, Aug 22 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 29 07:44 EST 2020. Contains 338756 sequences. (Running on oeis4.)