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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.

A260887 Sum over the genera g of the number of immersions of an oriented circle with n crossings in an unoriented surface of genus g.

Table of values

n a(n)
1 1
2 3
3 14
4 120
5 1556
6 27974
7 618824
8 16223180
9 490127050
10 16761331644
11 639969571892
12 26985326408240
13 1245476099801252
14 62451726395242858
15 3380720087847928728
16 196504354827002278248
17 12206388156005725243280
18 806977883623811932432386
19 56573396893818112613554940
20 4192088709829783508863131872

List of values

[1, 3, 14, 120, 1556, 27974, 618824, 16223180, 490127050, 16761331644, 639969571892, 26985326408240, 1245476099801252, 62451726395242858, 3380720087847928728, 196504354827002278248, 12206388156005725243280, 806977883623811932432386, 56573396893818112613554940, 4192088709829783508863131872]

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

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