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

1,3

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 76, Eq. (3.5.17).

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: A129442 A032347 A032346 this_sequence A058866 A087649 A123922

Adjacent sequences: A063686 A063687 A063688 this_sequence A063690 A063691 A063692

KEYWORD

more,nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 22 2001

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.


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