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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.

A008910 Join 2n points on a line with n arcs above the line; form graph with the arcs as nodes, joining 2 nodes when the arcs cross. a(n) is the number of cases in which the graph is symmetric about middle and has no isolated nodes.

Table of values

n a(n)
1 0
2 1
3 2
4 9
5 26
6 122
7 466
8 2299
9 10316
10 54179

List of values

[0, 1, 2, 9, 26, 122, 466, 2299, 10316, 54179]

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

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