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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.

A347257 Number of fixed hexagonal polyominoes with n cells that have a horizontal axis of symmetry that connects the midpoints of opposite edges of one of the n cells.

Table of values

n a(n)
1 1
2 1
3 3
4 4
5 12
6 18
7 52
8 83
9 235
10 389
11 1087
12 1849
13 5110
14 8871
15 24310
16 42884
17 116706
18 208559
19 564322
20 1019362
21 2744769
22 5003180
23 13415317
24 24644438
25 65839497
26 121769444
27 324271545
28 603304529
29 1602013491
30 2996240586

List of values

[1, 1, 3, 4, 12, 18, 52, 83, 235, 389, 1087, 1849, 5110, 8871, 24310, 42884, 116706, 208559, 564322, 1019362, 2744769, 5003180, 13415317, 24644438, 65839497, 121769444, 324271545, 603304529, 1602013491, 2996240586]

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

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