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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.

A056504 Number of periodic palindromic structures of length n using a maximum of three different symbols.

Table of values

n a(n)
0 1
1 1
2 2
3 2
4 5
5 5
6 12
7 14
8 33
9 41
10 90
11 122
12 259
13 365
14 756
15 1094
16 2233
17 3281
18 6642
19 9842
20 19813
21 29525
22 59292
23 88574
24 177527
25 265721
26 532170
27 797162
28 1595443
29 2391485
30 4785156
31 7174454
32 14352233
33 21523361
34 43053282
35 64570082
36 129150085
37 193710245
38 387440172
39 581130734
40 1162291121

List of values

[1, 1, 2, 2, 5, 5, 12, 14, 33, 41, 90, 122, 259, 365, 756, 1094, 2233, 3281, 6642, 9842, 19813, 29525, 59292, 88574, 177527, 265721, 532170, 797162, 1595443, 2391485, 4785156, 7174454, 14352233, 21523361, 43053282, 64570082, 129150085, 193710245, 387440172, 581130734, 1162291121]

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

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