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.

A243212 Number of ways to place 3 points on a triangular grid of side n so that no three of them are vertices of an equilateral triangle with sides parallel to the grid.

Table of values

n a(n)
2 0
3 15
4 107
5 428
6 1282
7 3198
8 7022
9 14020
10 26000
11 45445
12 75665
13 120960
14 186802
15 280028
16 409052
17 584088
18 817392
19 1123515
20 1519575
21 2025540
22 2664530
23 3463130
24 4451722
25 5664828
26 7141472
27 8925553
28 11066237
29 13618360
30 16642850
31 20207160
32 24385720
33 29260400
34 34920992

List of values

[0, 15, 107, 428, 1282, 3198, 7022, 14020, 26000, 45445, 75665, 120960, 186802, 280028, 409052, 584088, 817392, 1123515, 1519575, 2025540, 2664530, 3463130, 4451722, 5664828, 7141472, 8925553, 11066237, 13618360, 16642850, 20207160, 24385720, 29260400, 34920992]

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

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