A204259 - OEIS

A204259

Matrix given by f(i,j) = 1 + [(2i+j) mod 3], by antidiagonals.

1, 2, 3, 3, 1, 2, 1, 2, 3, 1, 2, 3, 1, 2, 3, 3, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 3, 1, 2, 3, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3

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OFFSET

1,2

COMMENTS

This data is used to specify the height of hexagonally packed cylinders in a triangle with open boundaries. Three cylinders that touch each other define a "triple" and water can be retained between these cylinders. A257594, A258445 and A259052 give a classification for such spaces. The links below ignore the inter-cylinder space retention and only consider the water retention above solid cylinders. - Craig Knecht, Jul 16 2015

LINKS

Table of n, a(n) for n=1..99.

Craig Knecht, Water retention triple.

Craig Knecht, Row sums of numbers completely surrounded by larger numbers (water retention) in A204259 = A008611.

Wikipedia, Water retention on mathematical surfaces

EXAMPLE

Northwest corner:

1 2 3 1 2 3 1 2

3 1 2 3 1 2 3 1

2 3 1 2 3 1 2 3

1 2 3 1 2 3 1 2

3 1 2 3 1 2 3 1