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A003025 Number of n-node labeled acyclic digraphs with 1 out-point.
(Formerly M2083)
5

%I M2083

%S 1,2,15,316,16885,2174586,654313415,450179768312,696979588034313,

%T 2398044825254021110,18151895792052235541515,

%U 299782788128536523836784628,10727139906233315197412684689421

%N Number of n-node labeled acyclic digraphs with 1 out-point.

%D R. W. Robinson, Counting labeled acyclic digraphs, pp. 239-273 of F. Harary, editor, New Directions in the Theory of Graphs. Academic Press, NY, 1973.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%e a(2) = 2: o-->--o (2 ways)

%e a(3) = 15: o-->--o-->--o (6 ways) and

%e o ... o o-->--o

%e .\ . / . \ . /

%e . v v ... v v

%e .. o ..... o

%e (3 ways) (6 ways)

%Y Cf. A058876, A003026.

%K nonn

%O 1,2

%A _N. J. A. Sloane_.

%E More terms from _Vladeta Jovovic_, Apr 10 2001

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Last modified August 9 05:12 EDT 2020. Contains 336319 sequences. (Running on oeis4.)