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A063689 Number of 2-trees rooted at a triangle with 3 similar edges. 0
1, 1, 2, 6, 21, 83, 356, 1599, 7434, 35381, 171508, 843419, 4197179, 21094355 (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. (3.5.17).

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

Sequence really begins 1, 0, 0, 1, 0, 0, 2, 0, 0, 6, 0, 0, 21, 0, 0, 83, 0, 0, 356, ... but only nonzero trisection is shown.

CROSSREFS

Cf. A005750, A058870, A058866, A054581.

Sequence in context: A329055 A148495 A150221 * A058866 A178325 A087649

Adjacent sequences:  A063686 A063687 A063688 * A063690 A063691 A063692

KEYWORD

more,nonn

AUTHOR

Vladeta Jovovic, Aug 22 2001

STATUS

approved

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Last modified November 29 08:27 EST 2020. Contains 338761 sequences. (Running on oeis4.)