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.

A243143 Number of inequivalent (mod D_3) ways to place 4 points on a triangular grid of side n so that they are not vertices of an equilateral triangle of any orientation.

Table of values

n a(n)
3 1
4 22
5 170
6 816
7 2947
8 8765
9 22703
10 52823
11 113042
12 225817
13 426299
14 766905
15 1324282
16 2206478
17 3563770
18 5599258
19 8584775
20 12875840
21 18934040
22 27347390
23 38860741
24 54402707
25 75125825
26 102441321
27 138070912
28 184090795
29 242997153
30 317760863
31 411908932
32 529591532
33 675681764

List of values

[1, 22, 170, 816, 2947, 8765, 22703, 52823, 113042, 225817, 426299, 766905, 1324282, 2206478, 3563770, 5599258, 8584775, 12875840, 18934040, 27347390, 38860741, 54402707, 75125825, 102441321, 138070912, 184090795, 242997153, 317760863, 411908932, 529591532, 675681764]

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

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