How to reference groups of rows in a matrix

I have a large matrix and want to reference certain rows of it all at once. For example,

Rows 130 to 255

Rows 258 to 383

Rows 386 to 511

and so on... all the way down to

Rows 1666 to 1791

So... groupings of 125 with a space of 3 apart.

I've tried a couple approaches, one being a combination of for and if loops using Boolean operators to exclude multiples of 129 and 128. I couldn't get this to work and would prefer not to use this method as I'll be repeating the process with gaps much larger than 3.

I've also tried a combination of colons but can't seem to get it right.

Answer 1

[Walter Roberson]

idx = 130:size(YourMatrix,1);
idx(127:128:end) = [];
idx(127:127:end) = [];

submatrix = YourMatrix(idx,:);