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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.

A289191 Number of polygonal tiles with n sides with two exits per side and n edges connecting pairs of exits, with no edges between exits on the same side and non-isomorphic under rotational symmetry.

Table of values

n a(n)
1 0
2 2
3 4
4 22
5 112
6 1060
7 11292
8 149448
9 2257288
10 38720728
11 740754220
12 15648468804
13 361711410384
14 9081485302372
15 246106843197984
16 7160143986526240
17 222595582448849152
18 7364186944683168828
19 258327454310582805036
20 9577476294162996275928
21 374205233351106756670120

List of values

[0, 2, 4, 22, 112, 1060, 11292, 149448, 2257288, 38720728, 740754220, 15648468804, 361711410384, 9081485302372, 246106843197984, 7160143986526240, 222595582448849152, 7364186944683168828, 258327454310582805036, 9577476294162996275928, 374205233351106756670120]

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

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