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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.

A056508 Number of periodic palindromic structures of length n using exactly two different symbols.

Table of values

n a(n)
1 0
2 1
3 1
4 3
5 3
6 6
7 7
8 13
9 15
10 25
11 31
12 50
13 63
14 99
15 127
16 197
17 255
18 391
19 511
20 777
21 1023
22 1551
23 2047
24 3090
25 4095
26 6175
27 8191
28 12323
29 16383
30 24639
31 32767
32 49221
33 65535
34 98431
35 131071
36 196743
37 262143
38 393471
39 524287
40 786697
41 1048575
42 1573375
43 2097151
44 3146255
45 4194303

List of values

[0, 1, 1, 3, 3, 6, 7, 13, 15, 25, 31, 50, 63, 99, 127, 197, 255, 391, 511, 777, 1023, 1551, 2047, 3090, 4095, 6175, 8191, 12323, 16383, 24639, 32767, 49221, 65535, 98431, 131071, 196743, 262143, 393471, 524287, 786697, 1048575, 1573375, 2097151, 3146255, 4194303]

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

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