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.

A056500 Number of primitive (period n) periodic palindromes using exactly four different symbols.

Table of values

n a(n)
1 0
2 0
3 0
4 0
5 0
6 12
7 24
8 132
9 240
10 900
11 1560
12 4968
13 8400
14 24588
15 40824
16 113520
17 186480
18 502248
19 818520
20 2157360
21 3497976
22 9085452
23 14676024
24 37723260
25 60780720
26 155082900
27 249401640
28 632947728
29 1016542800
30 2569816476
31 4123173624
32 10393520640

List of values

[0, 0, 0, 0, 0, 12, 24, 132, 240, 900, 1560, 4968, 8400, 24588, 40824, 113520, 186480, 502248, 818520, 2157360, 3497976, 9085452, 14676024, 37723260, 60780720, 155082900, 249401640, 632947728, 1016542800, 2569816476, 4123173624, 10393520640]