We prove a known 2-coloring of the integers
[
N
]
≔
{
1
,
2
,
3
,
…
,
N
}
[N] ≔\{1,2,3,\dots ,N\}
minimizes the number of monochromatic arithmetic 3-progressions under certain restrictions. A monochromatic arithmetic progression is a set of equally-spaced integers that are all the same color. Previous work by Parrilo, Robertson and Saracino conjectured an optimal coloring for large
N
N
that involves
12
12
colored blocks. Here, we prove that the conjectured coloring minimizes monochromatic arithmetic
3
3
-progressions among anti-symmetric colorings with
12
12
or fewer colored blocks. We leverage a connection to the coloring of the continuous interval
[
0
,
1
]
[0,1]
used by Parrilo, Robertson, and Saracino as well as by Butler, Costello and Graham. Our proof identifies classes of colorings with permutations, then counts the permutations using mixed integer linear programming.