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.

A199903 Number of -2..2 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2).

Table of values

n a(n)
1 1
2 4
3 12
4 24
5 82
6 232
7 654
8 2044
9 6096
10 18564
11 57500
12 177032
13 550098
14 1715956
15 5359158
16 16799508
17 52760640
18 165976252
19 523094304
20 1650781728
21 5216112586
22 16501009804
23 52252555938
24 165618780196
25 525388548976
26 1667965025692

List of values

[1, 4, 12, 24, 82, 232, 654, 2044, 6096, 18564, 57500, 177032, 550098, 1715956, 5359158, 16799508, 52760640, 165976252, 523094304, 1650781728, 5216112586, 16501009804, 52252555938, 165618780196, 525388548976, 1667965025692]

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

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