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.

A056490 Number of 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 4980
13 8400
14 24612
15 40824
16 113652
17 186480
18 502500
19 818520
20 2158260
21 3498000
22 9087012
23 14676024
24 37728372
25 60780720
26 155091300
27 249401880
28 632972340
29 1016542800
30 2569858212
31 4123173624
32 10393634292
33 16664094960

List of values

[0, 0, 0, 0, 0, 12, 24, 132, 240, 900, 1560, 4980, 8400, 24612, 40824, 113652, 186480, 502500, 818520, 2158260, 3498000, 9087012, 14676024, 37728372, 60780720, 155091300, 249401880, 632972340, 1016542800, 2569858212, 4123173624, 10393634292, 16664094960]