cp's OEIS Frontend

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.

A056309 Number of reversible strings with n beads using exactly two different colors.

Table of values

n a(n)
1 0
2 1
3 4
4 8
5 18
6 34
7 70
8 134
9 270
10 526
11 1054
12 2078
13 4158
14 8254
15 16510
16 32894
17 65790
18 131326
19 262654
20 524798
21 1049598
22 2098174
23 4196350
24 8390654
25 16781310
26 33558526
27 67117054
28 134225918
29 268451838
30 536887294
31 1073774590
32 2147516414
33 4295032830
34 8590000126

List of values

[0, 1, 4, 8, 18, 34, 70, 134, 270, 526, 1054, 2078, 4158, 8254, 16510, 32894, 65790, 131326, 262654, 524798, 1049598, 2098174, 4196350, 8390654, 16781310, 33558526, 67117054, 134225918, 268451838, 536887294, 1073774590, 2147516414, 4295032830, 8590000126]

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

Content is available under The OEIS End-User License Agreement.