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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A121063 Number of labeled directed multigraphs with n arcs for which every vertex has in-degree at least one and out-degree at least one.

Table of values

n a(n)
0 1
1 0
2 1
3 4
4 27
5 246
6 2783
7 37424
8 582153
9 10276452
10 202894801
11 4429522252
12 105943672079
13 2754788353526
14 77371821493913
15 2334279549290960
16 75286455363538607
17 2584971423426768872
18 94138234184851584599
19 3624294240897948371036
20 147080227272202880297669

List of values

[1, 0, 1, 4, 27, 246, 2783, 37424, 582153, 10276452, 202894801, 4429522252, 105943672079, 2754788353526, 77371821493913, 2334279549290960, 75286455363538607, 2584971423426768872, 94138234184851584599, 3624294240897948371036, 147080227272202880297669]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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