You will get some answers here but maybe not the ones you are looking for.
For example it lists the HC as "multicoated" and as being produced between Dec 1972 - Oct 1974. It lists the AI version as being produced between Nov 1974 - 1977 but makes no mention of its coating.
I have a sneaking suspicion though, that Nikon tweaked their multi coatings as they went along but (depending upon marketing intentions) did not always mention such changes explicitly.
The web page also states in relation to C lenses:
- Multi-layer coating on all lens surfaces - reflections colored dark green, red and purple.
- Engraving ".C" added to lens designation, except early 28/2 and 35/1.4.
- Barrel colored black, otherwise identical to late F type.
I think the "identical" reference refers to to exterior appearance not coating appearance. This supports my comment and those of rumbliegeos (below) that coatings were tweaked over time as made apparent by the differing reflection colors. In fact Nikon also adopted a system they called NIC or Nikon Integrated Coating described thus at the MIR site:
"Nikon Integrated Coating. In years past, the reflection of light off the surfaces of individual lens elements and the absorption of light into the glass itself caused a multitude of problems, including ghost images, flare, poor contrast, and unfaithful color rendition. Great strides forward were made in the early 1970's when various camera companies began applying multiple layers of microscopically thin anti-reflective materials to the lens elements.
However, unlike other manufacturers who indiscriminately apply the same number of coatings to each and every lens element regardless of its type or the glass used, Nikon's multilayer coating process is integrated into the design of the particular lens. Just the right number of coatings are applied to each lens element in a vacuum chamber to match the lens type and glass used. The result is a dramatic increase in image contrast and actual light transmission and a corresponding reduction in flare caused by internal reflections. But more importantly, uniform color balance from lens to lens is achieved throughout the entire Nikkor and Nikon Series E line-up. Yes, Nikon Integrated Coating (NIC) is not an easy process, but then optical excellence demands nothing less. "
It is not clear to me though when NIC was introduced (was it a feature of early Nikon multicoating?) and how much it changed over the years but I think it did change as newer processes became available. The color of the coating reflections are the hint.
Ken Rockwell also has a section on different Nikon coatings and their colors (about three quarters down the page) :