A003026 Number of n-node labeled acyclic digraphs with 2 out-points.

1, 9, 198, 10710, 1384335, 416990763, 286992935964, 444374705175516, 1528973599758889005, 11573608032229769067465, 191141381932394665770442818, 6839625961762363728765713227698

Offset: 2

Author

N. J. A. Sloane

Keywords

• nonn

References

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

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..50

Crossrefs

A diagonal of A058876.

Cf. A003025.

Programs

PARI

\\ requires A058876.
my(T=A058876(20)); vector(#T-1, n, T[n+1][2]) \\ Andrew Howroyd, Dec 27 2021

Extensions

More terms from Vladeta Jovovic, Apr 10 2001