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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.

A319158 Given an equilateral triangular grid with side n, containing n(n+1)/2 points, a(n) is the minimal number of points to be selected, such that any equilateral triangle of points will include at least one of the selection, if the triangle has the same orientation as the grid.

Table of values

n a(n)
1 0
2 1
3 2
4 4
5 6
6 9
7 13
8 18
9 23
10 29
11 35
12 43
13 51

List of values

[0, 1, 2, 4, 6, 9, 13, 18, 23, 29, 35, 43, 51]

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

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