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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.

A240441 Number of ways to place 4 points on a triangular grid of side n so that no three of these points are vertices of an equilateral triangle of any orientation.

Table of values

n a(n)
1 0
2 0
3 3
4 114
5 969
6 4773
7 17415
8 52125
9 135375
10 315675
11 676200
12 1352085
13 2553558
14 4595934
15 7937874
16 13229118
17 21369330
18 33579450
19 51487425
20 77229900
21 113571975
22 164046795
23 233117313
24 326362179
25 450688329
26 614572413
27 828333870
28 1104441975
29 1457859900
30 1906428300

List of values

[0, 0, 3, 114, 969, 4773, 17415, 52125, 135375, 315675, 676200, 1352085, 2553558, 4595934, 7937874, 13229118, 21369330, 33579450, 51487425, 77229900, 113571975, 164046795, 233117313, 326362179, 450688329, 614572413, 828333870, 1104441975, 1457859900, 1906428300]

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

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