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 A139623 Table read by rows: T(n,k) is the number of directed multigraphs with loops and no vertex of degree 0, with n arcs and k vertices, which are transitive (the existence of a path between two points implies the existence of an arc between those two points). 4
 1, 1, 1, 4, 3, 1, 1, 7, 12, 9, 3, 1, 1, 13 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Length of the n^th row: 2n. T(n,1) = T(n,2n) = 1 and T(n,2n-1) = 3 if n>1. Row sums: A139628. LINKS EXAMPLE Triangle begins 1, 1; 1, 4, 3, 1; 1, 7, 12, 9, 3, 1; CROSSREFS Cf. A136564, A139624, A139625. Sequence in context: A157464 A046546 A189967 * A278072 A216482 A080758 Adjacent sequences:  A139620 A139621 A139622 * A139624 A139625 A139626 KEYWORD nonn,tabf,more AUTHOR Benoit Jubin, May 01 2008 STATUS approved

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Last modified May 16 15:55 EDT 2021. Contains 343949 sequences. (Running on oeis4.)