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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.

A090860 Number of ways of 4-coloring a map in which there is a central circle surrounded by an annulus divided into n-1 regions. There are n regions in all.

Table of values

n a(n)
4 24
5 72
6 120
7 264
8 504
9 1032
10 2040
11 4104
12 8184
13 16392
14 32760
15 65544
16 131064
17 262152
18 524280
19 1048584
20 2097144
21 4194312
22 8388600
23 16777224
24 33554424
25 67108872
26 134217720
27 268435464
28 536870904
29 1073741832
30 2147483640
31 4294967304

List of values

[24, 72, 120, 264, 504, 1032, 2040, 4104, 8184, 16392, 32760, 65544, 131064, 262152, 524280, 1048584, 2097144, 4194312, 8388600, 16777224, 33554424, 67108872, 134217720, 268435464, 536870904, 1073741832, 2147483640, 4294967304]

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

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