Thread Subject: Anyone recognize these Lagrange coefficients?

I need experts eyes for this set of coefficients. I am new at this whole Fractional Delay Filter @ Farrow and Lagrange Interpolation. So any help will be much appreciated, especially with many MATLAB pros and elite mathematicians here.

The reason why I wanted desperately for this set is because I see it being used in various examples (in books, websites, and MATLAB help file), but the source of prior approximation was never given. I want to see if I can shadow their process from beginning to end. I learn better that way!

This mysterious set of coefficient can be found in Matlab DSP toolbox (dfilt.farrowfd)
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coeffs = [-1/6 1/2 -1/3 0;
               1/2 -1 -1/2 1;
              -1/2 1/2 1 0;
               1/6 0 -1/6 0];
Hd = dfilt.farrowfd(.5, coeffs)
y = filter(Hd,1:10)
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I am looking at a 4x4 coefficient set, with beautiful fractional numbers.

If you can lead me to any experiment, tutorial or sources where those coefficients can be see or explained, it will be much appreciated!

Many Thanks,

Kevin