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A063688 Number of 2-trees rooted at a triangle. 0
1, 1, 3, 10, 39, 164, 746, 3474, 16658, 81166, 401169, 2004517, 10110757, 51402250, 263133142, 1355126922, 7016115632, 36498130908, 190673015083, 999932115039, 5262094054524, 27779114013628, 147072756065567, 780722981065006 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 76, Eq. (3.5.13).

LINKS

Table of n, a(n) for n=1..24.

CROSSREFS

Cf. A005750, A058870, A058866, A054581.

Sequence in context: A253194 A151072 A151073 * A245378 A221585 A083862

Adjacent sequences:  A063685 A063686 A063687 * A063689 A063690 A063691

KEYWORD

nonn

AUTHOR

Vladeta Jovovic, Aug 22 2001

STATUS

approved

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Last modified November 17 07:44 EST 2018. Contains 317275 sequences. (Running on oeis4.)