How to interpret Index matrix in the OpenGl Cube example

I am new to OpenGl. I was trying to understand the Qt OpenGL cude example code. I am confused with the indices matrix in the geometryengine code. The index buffer values that i found over the internet where 36 size matrixes. But in Qt example it’s 34 size matrix. I found some thing related to degenerated triangle strips in one article. Still I am unable to connect the dots. I think this is not related to Qt, but can any one help me out in understanding how to arrive at those values. Is there any article in the internet related to the generation of index matrix that we are having in this example?