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A129524 Number of unlabeled digraphs on n vertices such that every vertex has outdegree 2. 6
0, 0, 1, 6, 79, 1499, 35317, 967255, 29949217, 1033242585, 39323062014, 1637375262965, 74075329383599, 3619112881630497, 189953824713590782, 10661151595417930874, 637230479685691806302, 40415532825383300892418, 2711124591869919503655096 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..50
L. Travis, [math/9811127] Graphical Enumeration: A Species-Theoretic Approach
CROSSREFS
Column k=2 of A329228.
Cf. A001373, A185193, A185194, A185303.
Sequence in context: A156929 A123796 A184553 * A131237 A024082 A132547
Adjacent sequences: A129521 A129522 A129523 * A129525 A129526 A129527
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, May 29 2007
EXTENSIONS
Terms a(10) and beyond from Andrew Howroyd, Nov 08 2019
STATUS
approved

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Last modified May 18 05:02 EDT 2024. Contains 372618 sequences. (Running on oeis4.)