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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.

A227116 Given an equilateral triangular grid with side n, containing n(n+1)/2 points, a(n) is the minimal number of points to be removed from the grid, so that, if 3 of the remaining points are chosen, they do not form an equilateral triangle with sides parallel to the grid.

Table of values

n a(n)
1 0
2 1
3 2
4 4
5 7
6 9
7 14
8 18
9 23
10 29
11 36
12 44
13 52
14 61
15 71

List of values

[0, 1, 2, 4, 7, 9, 14, 18, 23, 29, 36, 44, 52, 61, 71]

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

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