Color Palette question

How does the Palette # 0-55 work? Excel has 56 palettes, so if I try to change the palette using the ChangePalette method - giving it the RGB value and a palette index, does it mean that the color for the same R/G/B combination will be different based on the Palette index ?
If so, how does each palette index map to a particular base color?
Our application specifically needs to use R/G/B components and not the color name (i.e. no "ToHtml" or "FromHtml" mapping).
Thanks.

When you changed the palette, this color is added to palette and relace the old color. Excel.Colors will return all colors in the palette.