Lowest level a level 65 can group with and still get experience?

Titles says it all, I am wonderng what is the lowest level a level 65 character can group with and that low level character still get experience. Thanks for any information

43 = 2/3(65-1) rounded up (42.667)

With a minimum of 5 levels difference, and a maximum of 30, then anything in between follows this:
Highest = 1.5 * Lowest + 1 round fractional results down (with a minimum of 5 levels difference and a maximum of 30)
Lowest = 2*(Highest - 1)/3 round fractional results up

Table of Levels if math is not your strong suit, but it was done before the maximum of 30 levels was known.

Yther Ore.

That was very helpful thank you

I say level 44

My experience is there is no minus 1 in there.

To test that, could take an 85 and group with a 56, and see if that works or not. My vague recollection is the 56 would fail to get experience. I have a lame old 85 laying around, if someone has a level 56 they want to try it with.

I use a different method to calc it out, level + 1/2 level (lose any .5) + 1, so 43 + 21 + 1 = 65. I keep a 65 SK to PL characters from 43, and I have an 85 Ranger to PL characters from 56 (56+28 +1=85). and of course there is the max 30 level cap at higher levels. Below 43 I use my druid to do enhanced leveling.