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 A122078 Triangle read by rows: T(n,k) = number of unlabeled acyclic digraphs with n >= 0 nodes and n-k outnodes (0 <= k <= n). 2
 1, 1, 1, 1, 1, 2, 3, 1, 3, 11, 16, 1, 4, 25, 108, 164, 1, 5, 47, 422, 2168, 3341, 1, 6, 78, 1251, 15484, 88747, 138101, 1, 7, 120, 3124, 79836, 1215783, 7409117, 11578037, 1, 8, 174, 6925, 333004, 11620961, 199203464, 1252610909 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 REFERENCES R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976. LINKS R. W. Robinson, Rows n=0 through n=15, flattened EXAMPLE Under P = K the entry ( S, K-S ) : R gives the number R of unlabeled acyclic digraphs on K nodes with exactly S outnodes: P = 0 ( 0, 0 ) : 1 Total( 0 ) : 1 P = 1 ( 1, 0 ) : 1 Total( 1 ) : 1 P = 2 ( 2, 0 ) : 1 ( 1, 1 ) : 1 Total( 2 ) : 2 P = 3 ( 3, 0 ) : 1 ( 2, 1 ) : 2 ( 1, 2 ) : 3 Total( 3 ) : 6 P = 4 ( 4, 0 ) : 1 ( 3, 1 ) : 3 ( 2, 2 ) : 11 ( 1, 3 ) : 16 Total( 4 ) : 31 P = 5 ( 5, 0 ) : 1 ( 4, 1 ) : 4 ( 3, 2 ) : 25 ( 2, 3 ) : 108 ( 1, 4 ) : 164 Total( 5 ) : 302 P = 6 ( 6, 0 ) : 1 ( 5, 1 ) : 5 ( 4, 2 ) : 47 ( 3, 3 ) : 422 ( 2, 4 ) : 2168 ( 1, 5 ) : 3341 Total( 6 ) : 5984 CROSSREFS Row sums give A003087. Sequence in context: A065078 A203989 A126744 * A126736 A253257 A127412 Adjacent sequences:  A122075 A122076 A122077 * A122079 A122080 A122081 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Oct 18 2006 STATUS approved

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)